Character mistake: In the finals of Video Armaggeddon the compere keeps making comments such as "Jimmy loses a life and starts over in world two", "Laura finishes world two", "Lucas finishes world two". All three times the relevant person is actually in World 1 - Level 3. In Fact at no point are any of the competitors in World 2 and the only time any of them is out of World 1 is when Jimmy uses the warp to access World 4.
Continuity mistake: They get off a pickup truck after having hitched a ride. Then much later after having slept the night in a junkyard and hitched a ride with some motorcyclists they can be seen hitching a ride in the same pickup truck that dropped them off earlier in the film. (00:27:39 - 00:33:31)
Continuity mistake: When Sam is swinging the shovel at Putnam's car he busts the driver's side headlight twice.
Audio problem: At the Video Armageddon shortly after the event host first realises Jimmy isn't there, the female voice counting down the time proclaims "...the Video Armageddon will commence in T-Minus two minutes and counting". However, the digital timer on the stage is at precisely 01:00, not 02:00. (01:21:15)
Other mistake: At the bus station Hayley manages to score 25250 at Double Dragon. Jimmy needs to beat this score so Corey gets his $6.70. During the Double Dragon montage of Jimmy playing trying to beat Hayley's score, the first footage we see of the score, its already at 27850. Strangely Corey waits till Jimmy is at 29920 until he's satisfied that Hayley's score is beaten and he snatches her money from her hands.