Continuity mistake: Before Casey enters the lunchroom and until after he sits at the table and says, "We should do push-ups", the napkins in the holder (closest to the screen) are partially leaning toward the screen. When the camera shifts to an angled view of the napkin holder, the napkins that were leaning are straight up but some of the napkins on the opposite side are leaning (away from the screen). There also appear to be about half as many napkins. (00:49:30 - 00:50:07)
Continuity mistake: After Sensei puts Casey's white belt around his neck, the camera shifts to Sensei putting Casey's yellow belt on him - but the yellow belt has already been wrapped behind Casey and back to his front (ready to be tied). (00:34:30)
Continuity mistake: The lamp above the picture on the wall at the karate school/studio changes in appearance a few times. The first time Casey visited the school, the light bulb was covered by the lamp shade (which was aimed toward the picture); the bulb was not visible but it cast light onto the picture. When the picture was blurred behind Sensei, there was a round circle totally outside of the shade to represent the light bulb (which should have been inside the lamp shade and not visible). (00:15:30 - 00:27:17)