- SpongeBob SquarePants
- Patrick Star
- Gary the Snail
- Sir Urchin (debut)
- Snail Fail (debut)
The episode begins with Patrick going into SpongeBob's house to watch television with him. When he sees SpongeBob, he wonders what he's doing, leading to SpongeBob telling Patrick all about the wonders of reading books and the different kinds of books there are.
SpongeBob gives Patrick a book to read and he enjoys it a lot. Patrick ends up reading so many books that he becomes extremely intelligent. Unfortunately, Patrick's head is so big that he can't get out through the door, so SpongeBob starts to devise plans to get Patrick out.
SpongeBob tries several attempts to make Patrick's head smaller, but they all fail. Eventually he comes up with the plan to make Patrick dumber so his head shrinks, so he shows Patrick the Sir Urchin and Snail Fail show he was watching earlier to make him dumb again. The episode ends with Patrick losing all the knowledge he earned, only to start playing with the books again.
- Snail Fail hitting Sir Urchin with various objects, along with Sir Urchin yelling "Why you" and saying "What'd I do?"
- SpongeBob showing Patrick the different types of books.
|( ‣ ) Associated production music|
|( • ) Original music|
|( ◦ ) SpongeBob music|
• Another Best Day Ever - Nicolas Carr, Sage Guyton, Jeremy Wakefield [Title card]
‣ Welk Lounge - Vinnie Zummo [Zero-G Sample Libraries] [The Sir Urchin & Snail Fail Show!]
‣ A Casual Conversation - Nicolas Carr, Barry Anthony [Patrick looking for SpongeBob at his house]
‣ The Pollywog Strut - Nicolas Carr, Barry Anthony [Patrick imagines a playground for his mind]
‣ Welk Lounge - Vinnie Zummo [Zero-G Sample Libraries] [Patrick throws the TV downstairs]
‣ Lap Steel - Nicolas Carr [Transition to next scene]
‣ Seaweed - Steve Belfer [Patrick having fun in SpongeBob's library]
‣ Happy Links 6-9 - Paul Fenoulhet ["Oh, tender, naïve Patrick, it's not that kind of playground."]
‣ Seaweed - Steve Belfer [Patrick throwing books at SpongeBob]
‣ Parting of the Clouds - Nicolas Carr ["Behold the books, Patrick. Each one has a story to tell."]
‣ The Silver Blade - Ilona Sekacz ["Look Out! Those books are cliffhangers, stories for the adventurers."]
‣ Rule Britannia (a) - Dick Walter ["...Books with bridges!"]
‣ Fairies A - John Fox, Otto Sieben ["Listen to the soothing sounds of the Audio Books."]
‣ Unknown Track 89 - Dust ghost emerges from the book
‣ Fairies A - John Fox, Otto Sieben [Patrick trying to read a book]
‣ Harps and Bells - Nicolas Carr [SpongeBob turning pages]
‣ What's This - Nicolas Carr [Patrick's brain sees something]
‣ Bobbins and Spindles - Ronald Hanmer [Knowledge entering in Patrick's head]
‣ Symphony No. 5: Allegro Con Brio - Ludwig Beethoven [Patrick absorbing much more knowledge]
• Hot Steel and Slide Licks (s) - Jeremy Wakefield ["Uh, Patrick I think that's enough knowledge for one day."]
‣ The Museum Incident - Nicolas Carr ["Nonsense, dear boy."]
• Tension Bits - Nicolas Carr, Sage Guyton, Jeremy Wakefield [SpongeBob trying to stuff Patrick's head through the door]
‣ Hot Steel and Slide Licks (q) - Jeremy Wakefield ["You really got your melon jammed in there, didn't you?"]
‣ Mechanical Matinee - Sam Fonteyn [Patrick explaining SpongeBob how to solve the problem]
‣ Drama Link (c) - Hubert Clifford [SpongeBob connects an electromagnet to Patrick's head]
‣ Drama Link (f) - Hubert Clifford ["Gary! Speak to me!"]
‣ Harp Ding - Nicolas Carr ["Slime, that's it!"]
• Ripped Hide - Nicolas Carr, Sage Guyton, Jeremy Wakefield [Gary slimes Patrick's head]
‣ Vibe Q Sting - Nicolas Carr [SpongeBob sees "Head Shrinking for Beginners!"]
‣ ? [SpongeBob as witch doctor]
‣ Nude Sting - Nicolas Carr [SpongeBob's head shrinks]
• Hot Steel and Slide Licks (n) - Jeremy Wakefield ["I guess we'll have to live here in the library forever, Gary."]
‣ Goofy Conversation - Nicolas Carr, Barry Anthony [Patrick has the solution to the problem]
• Grass Skirt Chase - Sage Guyton, Jeremy Wakefield ["All right, Patrick, let's get stupid!"]
• Hot Steel and Slide Licks (r) - Jeremy Wakefield [SpongeBob plugs in the TV]
‣ Welk Lounge - Vinnie Zummo [Zero-G Sample Libraries] [The Sir Urchin & Snail Fail Show! again]
‣ Wheels Within Wheels - Ronald Hanmer [Patrick's knowledge is taken out of his head by a hose]
‣ Hot Steel and Slide Licks - Jeremy Wakefield [SpongeBob picks up Patrick's brain]
• Another Best Day Ever - Nicolas Carr, Sage Guyton, Jeremy Wakefield [Patrick's back to normal]
‣ Vibe Q Sting - Nicolas Carr ["A book?"]
• A Pineapple Luau with Bongos - Nicolas Carr, Sage Guyton, Jeremy Wakefield [Ending]
- This episode is available on the SpongeBob SquarePants Vol. 19 and The Complete Eleventh Season DVDs.
- This was the second episode to premiere during the September 2018 premiere week.
- It was also the highest-viewed episode in the event.
- This marks the 450th episode segment of the series.
- This marks the second episode where Patrick is smart, the first being "Patrick SmartPants."
- This is the second episode where SpongeBob is called "SpongeRobert." The first one was "SpongeBob LongPants."
- Ironically, despite being called "Library Cards," none are mentioned or seen in the episode.
- However, the title could be referring to SpongeBob and Patrick's antics in the library, as the word card also means "a person who is odd or amusing," which describes SpongeBob and Patrick.
- Patrick has visited SpongeBob's library before in "Boating School," "Something Smells," and "Sportz?," but he acts like he has never seen it until this episode.
- Furthermore, Patrick does not even know what the word "library" means at the beginning of the episode, but says he has overdue library books in "Rule of Dumb."
- Very little characters appear in this episode, with six in total making an appearance. Even less characters appear in-person, as Sir Urchin and Snail Fail are only shown on TV.
- A majority of this episode takes place inside SpongeBob's house, as the outdoors are only shown at the beginning of the episode for at least 30 seconds.
- This is one of the few episodes to showcase Gary's interest in reading, some others being "Sleepy Time," "Gary Takes a Bath," "Rock-a-Bye Bivalve," and "Pet Sitter Pat."
- He is shown reading a book called Cooking Without Salt, alluding to the fact that salt kills snails. This phobia was previously alluded to in "Pet Sitter Pat."
- This episode is mislisted on CBS All Access, instead of "Plankton Paranoia"/"Library Cards," it plays "Call the Cops"/"Surf N' Turf."
- An image of Patrick with a giant brain became a popular meme, usually used in memes about if someone's smart at inventing something, but it's mostly paired up with an image of Patrick with a piece of wood on his head (which shows the less smart part).
- When SpongeBob shows Patrick the contents of his library, he shows Leo Tolstoy's War and Peace as an example of an unabridged book.
- The novel is later referenced when a book called Clam and Peace appears.
- One of the books shown at the end of the episode is called Moby D, referencing Herman Melville's novel Moby-Dick.
- Another book shown is called The Old Fish and the Sea, referencing Ernest Hemingway's novel The Old Man and the Sea.
- At the start of the episode, the plank pathway between Squidward's house and the road is missing.
- When Patrick's brain first appears huge, his eyebrows are missing.
- In the French opening credits, Mr. Lawrence's name is misspelled as M. Lawrence.
- This also occurs in the French dub of "Patnocchio."
- In one scene a window is on the books from the library.
- The same error also occurs in "Glove World R.I.P."