When Kent is holding pigeon while attaching message he has the bird in his right hand. The scene immediately cuts to him holding the pigeon in his left hand.
The box with the pigeon changes from one with a removable lid to one with a hinged lid. Also, in several scenes the pigeon is obviously a fake bird.
Every time Kent leaves his office and approaches the Storage Room to become Superman, he first takes off his glasses and looks away from the door before opening it, without thinking that someone might already be in the Storage Room and accidentally learn his dual identity.
When the door in the jewelry store opens and closes, the striker or door latch does not move out to hold the door closed. Too, the characters open and close the door without turning the knob.
The crooks' invisibility device is hidden by a sliding panel. But given its location, the panel would be sliding across the outside of the door into the shack.
When Superman arrives at the shack he stares at the wall, but does not see the lead behind the sliding door that covers the control panel.