Errors made by characters (possibly deliberate errors by the filmmakers): At one point, Tugg says one actor may win a Teen Choice Award, and claims that "they'll slime you and everything!". Teen Choice Award winners get surfboards. The Nickelodeon Kids Choice Awards show is famous for sliming winners.
Errors in geography: In the opening moments, we are told the location is "South East Vietnam." Later the specific setting is Quang Tri. During the Vietnam War, Quang Tri was South Vietnam's northernmost province. After reunification, it was in the middle of the country. Either way, Quang Tri is not in eastern Vietnam.
Continuity: When Tugg Speedman talks to Kirk Lazarus, the backpack strap on his right shoulder is sometimes over the carabiner and sometimes beside it.
Continuity: During one of the Les' rampages via teleconference, his wedding ring disappears and reappears a couple of times.
Continuity: Before Kirk's group gets ready to set up camp after splitting up with Tugg, Jeff is seen holding his M60 by its strap. In the next shot, he's holding the weapon itself in both arms. In the next shot, he's holding it by the strap again.
Continuity: After Tugg Speedman's performance of 'Simple Jack', he is in a room cleaning off his makeup. When he wipes his face with a wet towel, most of the white is gone. However, when he turns around to meet little half-squat, it has reappeared.
Errors made by characters (possibly deliberate errors by the filmmakers): The Gap only sells merchandise under its own label; therefore, Alpa Chino could have not sold a line of "Alpa Chino chinos" at The Gap, as he claims.
Errors made by characters (possibly deliberate errors by the filmmakers): When Les Grossman is trying to make Rick Peck turn his back on Tugg, he calls the actor a white dwarf star headed for a black hole. White dwarf stars do not actually become black holes, but black dwarfs. Only the supernovas of giant stars create black holes.
Errors made by characters (possibly deliberate errors by the filmmakers): When Lazarus is talking to Tugg about 'Simple Jack' he claims that an actor should never go "full retard" and mentions Peter Sellers (Being There), Dustin Hoffman (Rain Man), Tom Hanks (Forrest Gump), and Sean Penn (I Am Sam) as examples. He claims that Sean Penn is the only one of those to go "full retard" and come away without an Oscar after being nominated. However, Peter Sellers did not win an Oscar for his role in Being There as well.
Errors made by characters (possibly deliberate errors by the filmmakers): When Tran says "Ni sher ben don Jack," he continues to say it as he turns to his crew/gang members, with "Ni" meaning "You." He should have said, "Tah sher ben don Jack," "Tah" meaning "He/She."
Revealing mistakes: When Jeff Portnoy sees the mountain of Heroin he runs over and puts his fingers up by it. If you look at his fingers you can clearly tell that he has already dipped his hands into the fixture; possibly from an earlier take.