Continuity mistake: Right after Jay and Silent Bob run off the Good Will Hunting 2 set from the security guards, they run outside and Jay's jacket is tied around his waist. Then, they run into the Scream movie set and he has his jacket on. As soon as they run out of the Scream movie set, his jacket is tied around his waist again.
Continuity mistake: During the scene where Brodie talks to Jay and Silent Bob about Bluntman and Cronic, he shows them a copy of Wizard magazine with a related article. On the right page is a picture of Holden and Banky. They then take this magazine and eventually show Holden McNeil the same article. The right hand pictures are different from how they were before.
Continuity mistake: During the shootout at the end, J and SB are hiding behind the car and a shot pierces the car between their heads. In later wide shots, the bullet hole is missing.
Continuity mistake: In the scene when Wildlife Marshall Willenholly joins the Utah Police in front of the Diner, the police cars move closer together and farther apart to allow for the marshall to walk from behind to in front of the cars.
Visible crew/equipment: When Ben Affleck is talking to Jay and Silent Bob in his 'Casa' near the start of the film, on the furthest shot you can see a guy or girl on the right of the reflection on the computer's coloured monitor. This is obviously a crew member because at one point, when Ben is talking, you can see the person moving around.
Revealing mistake: When the girls do their 'Entrapment' routine jumping through the lasers at the diamond vault, you can see them cut through the beams with their arms, legs, and hair.
Other mistake: During the credits of the movie, after Morris Day points to Jay and Silent Bob, there is an Asian guy jumping up and down at the far right hand corner. The shot switches back to Morris Day and when the shot goes back to Jay and Bob the Asian guy is wearing a light beige hat. The extra submitted this entry himself - he was wearing the hat during the shots. Then after several takes someone in costumes noticed it was a major logo ("No Fear") so he had to take it off. The shot was used before he had his hat on. (01:36:00)
Revealing mistake: When the girls are shooting at Marshal towards the end, in some shots you can see they aren't really pulling the triggers and that the muzzle-flashes have been added with special effects.
Continuity mistake: When Holden is reading the posts on moviepoopshoot.com, the right side of the browser window changes positions. It will change where the window takes up the whole screen, to where the window is smaller and you can see several icons to the right of the window.
Continuity mistake: Towards the end of the film when Jay and Silent Bob battle Mark Hamill, Jay cuts off Hamil's huge hand, and you see it drop to the ground, and you see his smoldering arm with no big hand. In the next shot when Mark Hamill is fed up and marches off camera, you see he once again has his huge hand attached to his body.
Other mistake: After Jay and Silent Bob catch a ride in the van with the quartet of diamond thieves and Brent, they say they are the Kansas State chapter of SAAC and they are headed to the Provasik Animal Testing Lab (located next to the Colorado Diamond Exchange, so therefore most likely in Colorado). The Mooby's restaurant is located in Kansas City, Missouri (as stated on the sign visible when Jay wakes up from his Scooby Doo nightmare). The Kansas State University campus is located in Manhattan, Kansas, which is about two and a half hours west of Kansas City. If the diamond thieves are headed west, to Colorado, then why are they stopping to eat nearly three hours out of their way to complete their mission? Even though the thieves aren't really from KSU, Brent was their patsy, meaning that he wasn't in on their plot, and therefore must himself have been from KSU; he would have no reason to lie to Jay and Silent Bob, given he tells them the truth about their mission (as far as he knows).
Continuity mistake: Near the end when Justice is talking to Federal Wildlife Marshal Willenholly after he's been shot by the orangutang, Justice's hand moves between shot. It goes from knee to floor and changes several times.
Continuity mistake: Near the beginning of the movie when Jay and Silent Bob are in the comic book store talking to Brodie, watch the man who is leaning against the wall reading the comic book. (the one Jay teases while walking past) In one shot he has the comic, then a second later he doesn't, and finally a second later he has it again and walks away. [For anyone who has seen or owns the 2 disc dvd of the film, and has watched the second disc, it will have tons of deleted scenes, including one for this scene. It shows Brodie having a go at the man for bending the spine of the comic book, and smacking the comic out of his hand. He then walks off, the guys feelings is hurt and leans against the wall, and the film continues.]