I love this movie so much, I've watched it too many times. In the scene where Dewey tells the class to put there hands over their hearts and say the "Pledge" to the band, the blond girl who is a groupie put's her right hand over her heart, but in a few shots, she'll have her left hand over her heart, and then back to right hand.
This may or not be a slipup, but I suspect that it could be deliberate to show her confusion, especially as the last part of the pledge is so long that the class ends up mumbling it.
Hey, just watched this movie yet again. The blonde kid who supposedly switches hands doesn't do it!! The shot with the 'reversed' hand is actually a classmate shot slightly out of focus. Watch it again.
No, actually, if you are paying attention, it's the same girl, and the cuts are too short for her to have had time to switch. Plus, he says, "Right hand" and they made a point of her holding her LEFT hand over her heart. It is a mistake that they should have caught.
The amount of time given between shots of the girl and Dewey are not long enough for the girl to have switched hands. In this case, this is a slip-up, because the director could have made sure that she kept the same hand on her heart the entire time.
Actually he doesn't say to put the right hand.
"I'm El Capitano! And what I say goes. So put your hands over your hearts."
You use lies to pretend you know more, when you are just LYING.