Continuity mistake: When the Terminator pulls John off the dirt bike during the drainage ditch chase, the dirt bike falls onto its left side and the gas tank is about to be crushed by the tow truck. The next shot from another angle shows the dirt bike laying on its right side, with the rear tire the first thing to be crushed under the truck. (00:37:30)
Continuity mistake: When the red Sunbird and the Caddy are driving sown the steep hill, the windshield on the Sunbird changes from passenger side busted out, to completely gone, to completely intact, when they hit the tree at the bottom. (01:18:15)
Revealing mistake: There's one scene where they are surrounded by the foot. Leonardo reaches behind him for his katanas, but he doesn't unsheath them. If you look at his elbows, you can see gaps in the pads where the actor in the suit hasn't fully fastened the gloves to the rest of the outfit. (01:05:40)
Plot hole: The assassin cuts a hole in the glass to kill the Federation president. But with the size of the hole and the placement of the scope on the phaser rifle, the assassin would not have been able to see out of the hole.
Other mistake: Michael McShane's name is spelled wrong ("Micheal") in the opening credits.
Revealing mistake: Near the start of the film, when Lt. Harley is watching his love interest show off by doing gymnastics on the tree limbs, several times you can see the actual pole she is swinging on, not the tree limb. (00:08:50)
Revealing mistake: Uncle Ghost sets a headstone in front of Ricky and tells him to break it with his energy. He breaks a small corner on the headstone with his hand to demonstrate, however it can be noticed that there are visible cut marks on the corner that he breaks off before doing so, revealing that the corner had already been cut off and reapplied to make it easier for Uncle Ghost to chop it off. (00:20:55)
Character mistake: Whoever wrote the "homicide" memo on the captain's corkboard spelled "homicide" wrong.
Continuity mistake: Towards the end of the movie, when the mob appraiser has verified the medallions are authentic, he is wearing two white gloves. He then asks if he can leave. When he stands up and gathers his things, he has only one glove on. The shot cuts away. When it cuts back to him, he has two gloves on again. (01:32:50)
Revealing mistake: When Angelo is shot in the back at the airport, you can see a pack underneath his shirt when he is rolled over by Utah. (01:39:44)