Revealing mistake: When Krypto is playing with Superman, he says, "Sit! Stay!" and then Superman's left foot suddenly stretches out unnaturally, like an oversized clown shoe. (00:06:57)
Suggested correction: I'm not sure this is a valid correction, but I'm also not sure this is a valid mistake. This appears to simply be a result of the camera lens creating some minor distortion at the edge of the frame, since it only happens when his foot reaches the corner of the screen. While it looks odd, I think it's dubious and debatable whether or not this is a "mistake", and opens a can of worms where any frame distortion, even intentional, could be considered a mistake. Not my decision, though.
Apparently, the effect is either a distortion caused by the curved LED wall they used or the lens. Whatever the cause, Superman's clown-shoe look was never meant to make it on screen. This site is littered with similar issues: lens distortions, colour mismatches, faulty rear projections, and more.
