Continuity mistake: When Silent Bob renders the demon disabled by using the anti-odour spray, you see him take the spray out of his coat and spray with his thumb. However, it cuts to a front view, and he is clearly seen using his index finger. It then cuts to Bob's rear, and he is, again, spraying with his thumb.
Continuity mistake: When Silent Bob carries Bethany's body back to the church after she's been killed by God's blast of lightning, watch her fingers when Silent Bob puts her down; she adjusts them to rest more comfortably on her arm.
Continuity mistake: When Bartleby and Loki go to the Mooby board room, Bartleby is listing the various Mooby products, and he forgets to mention the comic book. No one points out that he also never mentions the Mooby fast-food chain that we see the other characters at earlier in the film.
Continuity mistake: The writing on the second book from the left on the right of Bethany's bed changes colours in different scenes.
Other mistake: When Loki and Bartleby are in the Mooby boardroom, Loki sits back to continue carving the voodoo doll and tells Bartleby, 'You may proceed, mon ami.' As Bartleby stands up you can see that Loki has cut the head off his 'voodoo doll.'
Continuity mistake: In the Mooby HQ scene, the CEO tells one of his executives to call security. The executive's hand is right on the phone when Loki throws a knife into it. The movie cuts to a close-up of the phone but the executive's hand is nowhere in sight. It then cuts back and you can see the executive with his hand back on the phone, right before he pulls it away when the phone shorts out.
Continuity mistake: In the bar, when Azrael is doing his speech, everybody but Jay is listening to him; Jay is sleeping. It goes back to Azrael and he says something, the camera goes to Jay and he looks at Rufus, the camera then goes back to Azrael, and in the next shot Jay is sleeping again.
Continuity mistake: Look carefully when they transport to the Mexican Restaurant. Her night dress is unbuttoned at the top but mysteriously closes in a matter of seconds.
Revealing mistake: During Bartleby's "Prepare to taste God's wrath" diatribe, you can clearly see the seam along the front of his shirt that he uses to tear his shirt open revealing his armour. This seam is not seen at any other point in the movie.
Continuity mistake: When Bethany is being attacked by the "hockey players" outside of her job she is knocked down and her keys fall across a puddle. When the kid lines up his slapshot, there is no puddle. When the camera angle changes the puddle has returned.
Visible crew/equipment: When Bartleby and Loki are walking through the airport terminal, there are several poster frames on the wall in the background. In one of the highly reflective poster frames we can see the camera crew.
Continuity mistake: When everyone arrives at the church and Loki shoves Bethany away, one of her hair barrettes completely falls out, so half of her hair is down. When the camera shows her next, a few shots later, her hair is up again.
Continuity mistake: Towards the beginning when Bethany and the boys are in the diner, Bethany takes a big bite out of her muffin. But throughout the rest of the scene you can see it on the plate in front of her, and both pieces are whole.
Continuity mistake: During the fight on the train when Loki goes to hit Jay he decks him with a right cross but when he is shown from behind it looks as if he is starting an upper cut.
Visible crew/equipment: During the fight between Serendipity, Rufus, Jay and the others, in one part of the fight, you can clearly see the apparatus holding Ben Affleck's wings to his armour.
Continuity mistake: When Metatron is talking to Bethany, it shows that her phone is sitting almost right on top of a book. In the next shot of her, it is sitting right beside the book.
Continuity mistake: When Bethany runs into the water, her white sweater becomes see-through. In the next shot when 'the voice' starts to talk to her, it's completely dry.
Continuity mistake: Towards the end of the film, Jay takes off his pants in order to have sex with Bethany, as she promised. He takes them off, then in the next scene, from Bethany's angle, he is taking them off for a second time, when they had previously been around his ankles already.
Revealing mistake: During the final battle with Bartleby, when he turns to face the church/group, we can see Loki lying dead on the ground with his legs spread. At this point Loki moves his foot to a more comfortable position.