Continuity mistake: Dean finishes his absolute beatdown of the protagonist putting a knee on his back and choking him against a bench. He's holding the bench gripping the tip of the feet first. Deeper down in the next. (00:40:05)
Continuity mistake: Jason gets kicked over the buffet table. A girl in a dress watches the scene with one hand under her chin, both hands together, hands separate. (00:39:40)
Continuity mistake: When Scott throws the drink on the back of Jason's shirt, Kurt McKinney is casting a huge shadow right on the face of Dale Jacoby, unlike what happens when they talk. (00:39:05)
Plot hole: Kelly is a friend of Jason's from LA and they have been seeing each other since he transferred to Seattle (he mentions 'the other day' she saw something at the pet store). Basically the one passion in life Jason has, is karate. Her brother is the US karate champion, and yet Jason didn't know that or even that he was from Seattle. That's absurd on several levels, since it implies that he wouldn't know her last name (then how did they stay in touch?) and they never ever talked about anything personal, because it's fairly obvious it would come up really easily.
Continuity mistake: Ian Reilly approaches the three guys who called him over his own dojo. The goons on both sides have a different position between the two shots - for instance, the one to the boss'right does not and then does indeed have his hand on the ring. (00:37:00)
Continuity mistake: When Scott pervs Kelly and Jason making out, his right hand is down. In the closer angle when he holds back Dean though, his hand started already up, rubbing his belly. (00:36:35)
Continuity mistake: Kelly removes the ribbon from the package in close-up; it falls towards the camera, but in the previous shot her hand was sweeping the corner of the box away from that direction. (00:35:50)
Other mistake: In a quite extraordinary time compression, Jason receives the form, barely scribbles something on the first line, and the 'sensei' arrives and asks him "Finished?" And he says yes, without having written basically anything and surely not signed. (00:26:30)
Other mistake: In the world championship tournament shown on TV from the MGM Grand Hotel in Reno, the actual shots with the ring show a much smaller and poorly lit location that does not match the other footage. (00:24:20)
Factual error: The movie is set in Seattle for the most part, however in the parking lot of the burger joint you can see plenty nice palm trees planted all around it, in particular when RJ tries to escape. (00:21:30)
Continuity mistake: Scott white-knights the poor RJ that is being cradled into oblivion by the bulky bully. He jumps over the railing and kicks Scott; obvious is the lack of continuity; the guy with the striped white and green shirt that had folded arms and now is just standing there with his arms low is very obvious, but Scott himself was holding RJ by the thigh and in the second shot, to facilitate the kick, he is holding it by the far end of the leg. (00:22:05)
Continuity mistake: RJ tried to kick Scott away but only pushed himself off the table. Scott picks him up; the light of the two shots is blatantly different. (00:21:50)
Continuity mistake: When Scott backs RJ against the railing in front of the burger joint, some fellow bullies in the background change position between shots (the dude with the little ponytail had his left arm raised in guard and it's down, the guy with the horizontal stripes is suddenly with folded arms). (00:21:40)
Continuity mistake: Scott begins scarfing the burgers; instantly he gets a bunch of mayo and ketchup on his thumb, but it's gone at the cut. (00:20:10)
Revealing mistake: When RJ skates by the construction site, the actual skater is quite obviously a taller stuntman in a wig. (00:17:00)
Continuity mistake: When Scott gets RJ with the pressure washer, he wets the left side of his shirt - but in the hijinks by the road constructions, RJ sports a T-shirt wet on his right side. (00:16:45)
Continuity mistake: RJ is skating away from an angry Scott he just bit. In the sequence with two construction workers and a ladder, the natural light changes completely between shots (no direct sunlight at the beginning, clear shadows and sunny area in the close-up of the board tricks). (00:16:55)
Continuity mistake: Scott hoses RJ with the window cleaning machine; in the first shot RJ is really close to the fence, but the skateboard slips on sidewalk that is somehow already wet. Then Scott sits on him and begins brutalizing him, with the cement around RJ's head that is wet or dry depending on the shot, and when he gets up it's like they never fought with any water involved, the sidewalk is all dry. (00:16:35)
Continuity mistake: The obese comic relief is mocking his dad's speech as he puts him to work washing windows. At the first cut when he approaches the window you can tell time (and takes) passed, because the wet area on the wall under the window changed size considerably. The wall even basically all dries up the moment Scott spots RJ. (00:16:05)
Continuity mistake: The protagonist is all hyped-up because of his planned cemeterial trip. He begins training in his garage; when he kicks both the punching bag and the speedball, or at least attempts to, the mats on the floor change position between shots. (00:15:00)
