Continuity mistake: When Lance and Seth Green are riding in the buggy, they are talking for a few minutes. During this time the side shot will show Lance with his arm all the way around Seth's back/shoulder. However, when the camera changed to a full shot, Lance's arms were at his side, nowhere near Seth's back or shoulder. This happened several times during this scene. (00:40:35)
Revealing mistake: The shot of the two girls ripping open their shirts at the Fall Out Boy concert is the same clip repeated the three times we see them. (00:58:00)
Visible crew/equipment: When the GTO is driving to Knoxville, there are a few shots of the GTO passing other cars. When we see the black convertible with 2 girls in it, look in the black paintwork and you can see the camera boom clear as day. (00:35:45)
Continuity mistake: When the three of them are about to leave jail and Ian reads the message on his iPhone, the time says "August 14, 2008 10:02 PM". Later on, when Ian is in the car waiting for Ms_Tasty, the time says "12:02 Saturday, August 14". The date should be 15 August as it is after midnight (you can tell that this is late night/early morning as it is dark out and the time earlier was PM).
Factual error: When we see the impression from the radiator cap that shot into Ian's forehead, it says 'HOT'. Since the word 'HOT' was written correctly on the radiator cap, the word on his forehead should be backwards and read 'TOH', not 'HOT'.
Continuity mistake: Ian throws his list of things to take in the bin with it sticking out the bin when the camera cuts away. In the next angle there is nothing in the bin. (00:29:45)
Continuity mistake: When Lance and Ian are in jail, Lance is sitting next to a large man who is slouched forward. While Lance is mid-sentence, the shot changes and the man is sitting up much straighter. (01:11:45)
Continuity mistake: When Rex slams on his brakes after Ian tells him that he met a girl online, the background outside the driver side window is a building with trees around it. The shot then switches to the passenger side. When the shot goes back to the driver's side, the background outside of the window is just trees and other shrubbery, even though the car is still at a standstill. (00:06:25)
Continuity mistake: Just before Ian hits the possum with the GTO, Felicia's bottle changes hands instantly. (01:23:45)
Continuity mistake: When the GTO is racing the green car, the other cars around them change instantly and several times. (01:23:30)
Continuity mistake: When the GTO has the nachos chucked on the windscreen, the wipers are going in some shots but not others. (00:36:30)
Audio problem: In the cornfield, after Rick has run Lance over in his truck, Rick gets out and walks towards Lance saying, "Get on your feet, you....!" Although the shot is shown upside-down it is quite plain that his lips are not moving. (00:33:50)
Factual error: There are several mistakes relating to the Youtube video from the abstinence talk. Firstly, the user joined two minutes ago, and has 11 videos already. Secondly, his one video has over 5.2 million views, in less than two minutes. (01:17:10)
Continuity mistake: When Rex catches up with Ian at the motel, Ian's shirt is undone. When Ian leaves to meet the girl off the net, his shirt is done up. (01:36:25)
Deliberate mistake: When Seth Green and Lance pull up to Ian and Felicia, the car being pulled by the carriage should roll a little bit after the carriage stops moving, but instead it stops on a dime when it is only being pulled by rope, and nothing else to stop it with when the carriage stops. (00:42:00)
Factual error: When Ian has the gun while he's in the doughnut suit, he manages to fire it. But the fingers are so big, there is no way it could possibly fit into the trigger guard to be able to pull the trigger.
Visible crew/equipment: When the camera is panning the GTO at the end, the camera can be seen in the chrome bumper. (01:55:15)
Continuity mistake: When Rex is smashing up the garage door, his helmet keep changing position instantly. (01:08:20)
Continuity mistake: When Ian is driving the GTO to Knoxville, He pulls out into the middle lane on the bridge, camera cuts and he moves out again. (00:35:15)
Continuity mistake: When Ian chucks his list of things to take in the bin, the bin's position relative to the table leg changes instantly. (00:29:50)
Answer: LoJack.