Sometimes the wires that are holding up Mothra are visible .
If you look closely , you can barely see the guide wire for the missile when it's fired .
While the natives are sitting around in the temple where Mothra's egg is held, one of the tribesmen (Played by Akira Yamada) loses his geisha wig at the end of the sequence while rolling his head in a circular motion while sitting on the floor. He quickly grabs it back from the floor with the camera cutting to Mothra's egg 1 second too late.
When Mothra is destroying Newkirk City, the site of the action repeatedly returns to show various shots of destruction in front of the "Newkirk Motors" building.
When Dr. Shinichi is showing the symbols he discovered in the cave to Senchan, you can see someone in black pants and shoes walking down the stairs behind Senchan's head.