- French narrator
- Gary the Snail
- SpongeBob SquarePants
- Patrick Star
- Squidward Tentacles
- Incidental 103
- Incidental 47
- Sandy Cheeks
- King Neptune (mentioned)
- Eugene H. Krabs
In the beginning of the episode, SpongeBob and Patrick are dancing at SpongeBob's house. The music is shaking Squidward's house, so Squidward becomes annoyed and tells SpongeBob to lower the volume. When they do not listen, Squidward plays a squeaky tune, which sends SpongeBob and Patrick flying into Squidward's house. SpongeBob hits Squidward, lodging his clarinet in his throat, which makes Squidward produce squeaky notes. When SpongeBob gets the clarinet out of Squidward's throat, the reed is still stuck in him and Squidward blames SpongeBob. Then they go to see Sandy, who has a plan. She decides to go in a submarine, shrink herself and the submarine, go into Squidward's body, and retrieve the reed.
When Sandy goes to get some acorns and nuts from her treedome, she tells SpongeBob to guard the submarine. Patrick walks by and tricks SpongeBob into guarding the submarine from the inside. They go in there and guard it when Patrick presses the shrink button, shrinking the submarine. Sandy comes back and notices them. She then has to guide them to Squidward's brain. There, SpongeBob and Patrick start to hit parts of the brain, making Squidward lose self-control.
For a moment, SpongeBob and Patrick actually fight each other for control of the vehicle and land in Squidward's stomach, where the gastric acid starts to eat the submarine away. Patrick thinks of an idea: If Squidward can drink soda, then bubbles (gas) would surround them and it would refuel the submarine. Squidward drinks soda and then suddenly burps, creating bubbles. They travel through the throat where SpongeBob removes the clarinet reed by doing what he was "born to do," dance. The reed is removed and the gang celebrates, but is cut short by the sound of the now angered Squidward. He demands them to leave his body and yells at them to "GO!" However, Patrick mistakes it for "grow" and hits the grow button while still being in Squidward's body.
Squidward is next seen at the Krusty Krab looking bloated and his stomach in the shape of a submarine. A flush sound is then heard, followed by Patrick, still stuck in the submarine in Squidward's body, claiming the toilet is clogged (again, apparently). Squidward groans, as the episode ends.
|( ‣ ) Associated production music|
|( • ) Original music|
|( ◦ ) SpongeBob music|
‣ Maui Girl - Harry Bluestone [title card]
• SpongeBob Rocks the House - Nicolas Carr [opening]
• Squidwerds Clarinetitis - Nicolas Carr, Barry Anthony [Squidward playing clarinet]
• SpongeBob Rocks the House - Nicolas Carr ["SpongeBob, turn that noise off!"]
• Squidwerds Clarinetitis - Nicolas Carr, Barry Anthony [Squidward playing clarinet again]
‣ Dramatic Impact 2 - Ivor Slaney [SpongeBob slams into Squidward]
• Vibe Q Sting - Nicolas Carr ["Oh."]
• Tension Bits - Nicolas Carr, Sage Guyton, Jeremy Wakefield [SpongeBob trying to get the clarinet out of Squidward's throat]
‣ The March of the Ants - Sidney Crooke [x-ray of Squidward's throat]
‣ Haunted - Rick Cassman, Vyv Hope-Scott [Sandy's submarine]
• Steel Licks 12 - Jeremy Wakefield ["Always wanting to do it the hard way."]
• Nude Sting - Nicolas Carr [Sandy knocks Squidward out]
• What's This - Nicolas Carr ["Oops!"]
• Guarding the Sub - Nicolas Carr [SpongeBob guarding Sandy's submarine]
‣ Planet Surface - Gregor F. Narholz [Submarine opens up]
• Reporting for Duty - Nicolas Carr ["SpongeBob and Patrick reporting for guard duty."]
• Cream Pie - Sage Guyton, Jeremy Wakefield [SpongeBob, Patrick enter the submarine]
‣ Project X - Cedric-King Palmer [submarine shrinking]
‣ Secret Shadow - John Scott [submarine put into Squidward's nose]
‣ Lovely Scenery C - Mladen Franko [Squidward screams]
‣ Cosmic Cloud - Trevor Duncan ["SpongeBob and Patrick are piloting a miniature submarine inside my head?!"]
‣ Project X - Cedric-King Palmer [Squidward panicking]
‣ Weird Bridge - Roger Roger ["Where are we, Patrick?"]
‣ Drama Link (F) - Hubert Clifford ["I'll save you, Sandy!"]
‣ Moon Walk - John Fox [submarine breaks down]
‣ Dramatic Cue (C) - Ronald Hanmer [SpongeBob floors it]
‣ Missile Disaster - John Fox [submarine stuck in Squidward's brain]
• Steel Licks 9 - Jeremy Wakefield ["Oh, just your autograph."]
‣ On Fire - Gregor F. Narholz [Squidward hitting himself]
‣ Danger Force - Norman Dane [submarine lands in Squidward's stomach/Patrick has an idea to escape from Squidward's stomach]
‣ Exciting Action B - Mladen Franko [Squidward burps]
‣ Missile Disaster - John Fox ["Whee!"]
• Lap Steel - Nicolas Carr [Sandy smells Squidward's breath]
‣ Danger Force - Norman Dane [Squidward's esophagus]
• Flashback - Nicolas Carr [two hours later]
‣ Danger Force - Norman Dane ["This stupid hammer won't break anything."]
‣ Wild Panic [#40.02] - Gregor F. Narholz ["Whirlpool spin!"]
• Steel Sting - Jeremy Wakefield [Squidward coughs up the reed]
• What's This - Nicolas Carr ["Grow?"]
‣ Drama Link (B) - Hubert Clifford [everyone screams]
‣ The Tip Top Polka/The Cliff Polka - Chelmsford Folk Band [The Krusty Krab]
‣ Drama Link (F) - Hubert Clifford ["Neptune's trousers!"]
‣ Drama Link (D) - Hubert Clifford [Squidward with a submarine-shaped body]
‣ The Tip Top Polka/The Cliff Polka - Chelmsford Folk Band ["What's gotten into you?"]
‣ Captain Lenoe's - The Folk Players [ending]
- This episode is available on the Season 4 Volume 2, Complete Fourth Season, The Ultimate SpongeBob Box Set, The SpongeBob SquarePants Collection, 2-Season TV Pack, Slimy Dancing, The SpongeBob SquarePants 8 Season DVD Collection, On the Road Again, From the Beginning, Part 2, First 100 Episodes, SpongeBob SquarePants Vol. 6, The Third & Fourth Seasons, The Best 200 Episodes Ever, and Nautical Nonsense and Sponge Buddies (Turkish) DVDs.
- "Squidtastic Voyage" was ranked #47 during the SpongeBob's Top 100 event in the UK and Ireland from June 4-8, 2012.
- This is Clint Bond's first episode as a storyboard supervisor, replacing Sherm Cohen from this position.
- The beginning of the episode is similar to the main plot of "Jellyfish Jam," in that SpongeBob's loud music makes Squidward angry.
- This is the first time Squidward went into Sandy's treedome.
- This is the second episode in which Squidward swallows his clarinet. The first was in "SB-129."
- This was indirectly mentioned when SpongeBob says "You've swallowed your clarinet again."
- When the submarine is bouncing inside Squidward's skull, the blue sparks are piezoelectricity, the body is electricity.
- This is the first episode to play the track "Tension Bits."
- This is the second episode to involve shrinking. The first is "Mermaid Man and Barnacle Boy IV."
- In the Hebrew dub, this episode is called "יום בתוך סקווידוויד" translating to "Day inside Squidward."
- In the Greek dub, this episode is called "Ένα καλαμαρένιο ταξίδι" translating to "A Squid Trip."
- There is an online game based on this episode called InvasiVoyage.
- The quote "Sweet dreams, partner." would later appear in the online game Reef Rumble.
- The x-ray of Squidward's reed stuck in his throat is later seen in the online game Pet Vet.
- The sound when Squidward starts choking is heard in the online game Camping Chaos!
- The music "SpongeBob Rocks the House" at the beginning of the episode was used in the video game Grand Theft Auto III.
- The title and plot of this episode is a reference of the 60s film Fantastic Voyage.
- This is the ninth Nicktoon to parody the film. The first is "The Inside Story," from the Rugrats, the second is "Blazing Entrails" from The Ren & Stimpy Show, the third is "Internal Affairs" from Aaahh!!! Real Monsters, the fourth is "Fantastic Voyage" with The Angry Beavers, the fifth is "Fishing for Trouble" from CatDog, the sixth is "Tiny Timmy" from The Fairly OddParents!, the seventh is "NanoZIM" from Invader Zim, and the eighth is "Journey to the Center of Carl "from The Adventures of Jimmy Neutron, Boy Genius.
- The dance music is based on the song "Floating Waves" by Roadrunner.
- In reality, the mouthpiece was the piece stuck in Squidward's throat. The reed is attached to the mouthpiece which vibrates to make a sound out of an instrument. The reed is also a brownish-yellow and not black, which is the color of the mouthpiece.
- The actual piece to describe the reed was shown in "Best Day Ever."
- Squidward cannot stop making clarinet noises in the beginning because he swallows the whole clarinet at first, yet he can speak just fine in Sandy's submarine lab.
- In the first scene of the submarine, it looks like it is on an open platform, but later starting in the scene with SpongeBob guarding the submarine, it looks like it is in a room.
- In the first shot of the submarine, Sandy's tail is missing. In the next shot, it comes back.
- When SpongeBob and Patrick are saying "Whee!" in the submarine, SpongeBob blinks his eyes, but his eyelashes are still seen.
- When Squidward burps, Sandy smells it, even though she is wearing her helmet.
- When SpongeBob says, "Whirlpool spin!," his mouth does not move.
- When SpongeBob cuts the reed in half, red electricity is randomly seen for less than a second.
- SpongeBob and Patrick were in Squidward's throat when they got the reed out but when the submarine grew inside Squidward, the submarine was in his stomach.