Revealing mistake: When Daniel is running from Johnny and his gang after the bathroom incident at the dance, there's a lot of fog outside. If you look at one of the trees in the background, you can see that all the fog is being puffed out from behind the tree - obviously a fog machine.
Visible crew/equipment: In the sequence where the young are in the field to clear up the rules of "chicken game" (or something), you can see a part of a microphone above them.
Revealing mistake: Trish jumps out the window and lands face up on the ground. You can plainly see it's Kimberly Beck's stunt double. She looks nothing like her. (01:21:35)
Continuity mistake: The first car he jacks is a white 4 door Oldsmobile Cutlass salon, and a 2 door Olds Cutlass Supreme in the next. (00:09:30)
Revealing mistake: When the TVs explode, the glass is very fake and "cardboardy".
Factual error: In the very beginning sequence, as the riders are galloping triumphantly across the mighty windswept plains of yore to capture Conan, you can see power lines in the background in one brief shot at the very left of the screen.
Visible crew/equipment: When the two lead characters pull up to a stop in the car, the shot is dead-on from the driver's side, and you can clearly see the entire camera crew reflected in the side of the car. (00:30:10)
Revealing mistake: There are two Ewoks Wicket's parent is in search of. One of the those Ewoks is climbing down a mountain and the other has finished climbing down. As this happens, look at the Ewok not climbing. As he bends down, half way down his left leg, there is some sort of fold there. This is mainly due to the fact that the Ewok actors wore costumes whilst filming. The fold is coming from the Ewok costume. (00:07:50)
Visible crew/equipment: When the PI enters the house for the first time to take the pictures, when he goes back outside you can clearly see a crew member standing off to the right of the frame. May only be visible in widescreen.
Continuity mistake: When Warren is playing the electronic chess game, the hand on the chess arm that Warren shakes after the game appears from nowhere.
Continuity mistake: At the end, after Mahoney kisses Karen, she takes off her hat and the position of her fringe changes between one angle and the other.
Continuity mistake: Alex comes to work very hungover. He proceeds to spill coffee on his shirt twice. He then talks with Lisa in his classroom and now the shirt is clean.
Revealing mistake: When Harkin Banks almost loses control and skis through the lodge, the jump ramp is visible as the woman opens the door. (01:29:45)
Factual error: According to "The Doomsday Machine", full impulse drive is one-quarter the speed of light. In the first two movies, Enterprise used thrusters as opposed to impulse drive to leave Spacedock, confirming the notion that impulse drive is far too fast to leave such a (comparatively) small structure. Styles, however, orders Excelsior to one-quarter impulse, which is 18,750 km/s. In one second, she will travel half again Earth's diameter. From the time he gives the order to the time we see Excelsior clear spacedock's doors is approximately 40 seconds. Even allowing 30 seconds to go from rest to one quarter impulse, spacedock must be 13-15 times bigger than Earth! That's some serious engineering. (00:23:45)
Suggested correction: I reckon the writers always refer to levels of "impulse power" precisely so they don't have to worry too much about particular speeds (personally I always thought of it as roughly analogous to gears on a vehicle, but your mileage may vary). They use impulse to leave dock in both Star Trek II: The Wrath of Khan and Star Trek VI: The Undiscovered Country (it's implied to be unusual in both cases, for what it's worth). If all of that contradicts an earlier episode, I think we're looking at more of a retcon situation than a mistake.
Suggested correction: The warp scale has been adjusted several times, so it is impossible to say precisely how fast this fictional technology is, and by extension, how fast impulse is.
Impulse drive speed on starships have been consistent. Although sometimes quarter impulse on a shuttle refers to quarter power and not speed. Even if the speed of quarter impulse is 10 times slower than suggested (and used in the series), spacedock would still be 1.3-1.5 times bigger than Earth, which it wasn't. "It's fictional technology" is usually only a valid correction if the technology isn't explained in-universe. However, when certain parameters regarding fictional technology are established (even if they set wide parameters such as warp speed velocities) violations or contradictions (through bad script writing or whatnot) are valid mistakes.
Continuity mistake: During the second "break fight" against Electro Rock in the club, there is a shot of Turbo wearing a grey windbreaker while Ozone is dancing. In the next shot he is putting the jacket on and when Kelly gets on the floor, the jacket is nowhere in sight.
Continuity mistake: When Matthew is shaving and Jennifer is distracting him, the cut on his cheek changes position throughout the scene.
Revealing mistake: When the guy on the horse pulls out his sword, he has trouble getting it out of the sheath at first and it bends severely. It is clear that it is not a real sword.
Continuity mistake: At the beginning of the movie, Selena drives her car to the right side of the house. When the shot changes, the car is several feet further back and is now heading across the front of the entrance.
Other mistake: In the beginning of the movie, when the mechanic is working on the car on the lift, he says he has to change the oil in it, the chassis drops to the ground, there is no engine attached to the chassis or body. In addition, he is changing the oil at the rear axle.
Continuity mistake: In the scene where Hector is talkin to Samantha and Regina in the radio station, just after they met, Hector is taking off his gloves. Then they switch over to the girls and when they switch back to Hector, his gloves are back on and he starts taking them off again.