Continuity mistake: When the boys are on the Nemesis Inferno, Will sits at the front while the rest sit behind him, and this leaves the right outside seat free. However, when the roller coaster is moving, the mounted camera shows that Simon, Jay and Neil have all moved one seat to the right, meaning that Simon is now on the right outside seat instead of it being free.
Deliberate mistake: In the scene where Jay spots the "car full o' muff" and they follow the car until it turns left (just after Jay says he'd "give a left bollock for em"), when it pulls away, the shot is flipped. The number plate is reversed, all of the logos on the back of the car are backwards, and the car is actually turning right, as it heads to the right hand side of the road. The shot is just flipped to make it look like they're turning left.