Trivia: Both Brody Bruce and Randall Graves (from Clerks) have a cousin named Walter. In Clerks Randall tells Dante about his cousin Walter breaking his neck trying to suck his own d**k. In Mallrats Brodie starts the movie by telling you a story of how his cousin Walter kept shoving cats up his ass to get a gerbil out of there.
Trivia: LaFours the security guard who wears the white straw cap is a reference to LaFours in Butch Cassidy and the Sundance Kid who also always wears a white straw cap.
Trivia: OK, this isn't a mistake, just a strange coincidence. If you have the DVD, and you listen to the commentary, at one point Kevin Smith talks about a scene that was cut from the script where Jay and Silent Bob are watching Gwen in the changing room and that they are "pleasuring themselves." He then mentions a substance landing in her hair, and how he was told to take it out because it was vulgar. He goes on to bring up how much "There's Something About Mary"'s famous scene is akin to his cut scene, and how TSAM went on to make $200 million. Now, if you pay attention to the scene where Brodie and Rene are having sex in the elevator, the song playing is "Build Me Up, Buttercup" - the same song that plays over the credits of TSAM.
Trivia: When Jay and Bob attack the Easter bunny, have a look towards the end of the attack. Bob begins to chew on the bunny's ear. Pretty pointless considering it's part of the costume and wouldn't hurt the guy inside it at all.
Trivia: After Jay fills one of his socks with quarters and gives it to Silent Bob, he is only wearing one sock throughout the rest of the film.