Revealing mistakes: After Trevor is hit by the VW Bug, the arm he lands on disappears somewhat into the street, making the CGI obvious.
Continuity: In the bathroom of The Boiler Room, Trevor knocks down the right soap dispenser. However, in the next shot it hangs on the wall.
Crew or equipment visible: While sitting in his truck at the airport terminal car park (1hr 19 mins) the feet of the cameraman can be seen briefly in the truck's metallic wing mirror.
Continuity: When Trevor opens his past due utility bill, the due date says July 27th, yet a couple scenes later he's discussing Mother's Day plans with the waitress at the cafe.
Continuity: In the driving sequence after Trevor is asked if he has had any head injuries, the cigarette lighter position changes between the time it is pushed from when it pops out.
Continuity: When Resnik pulls up in his truck outside Miller's house he parks a couple of feet from the kerb, when he returns the truck is tight against the kerb.
Revealing mistakes: The same RV that is in front of Miller's house, is used in another scene, where Trevor is existing the tunnel, and nearly hits an RV. It is the same RV.
Errors made by characters (possibly deliberate errors by the filmmakers): When playing "Hangman," a part of the body is drawn only after a wrong letter has been guessed; in the movie, Trevor draws a body part before filling in a letter.
Revealing mistakes: The energy bill that Reznik opens, 20 minutes into the film, shows the unlikely meter number of "123-456789". Presumably it was hoped this would not be spotted with the distraction of the large FINAL NOTICE above it.