Megalon's ray beam is animated the same way as King Ghidorah's gravity beams. This was made to ensure that stock footage from Ghidorah's movies could easily be interspliced between shots of Megalon firing his beam. See more

Goofs

The opening scene at the lake was supposed to take place on a warm, probably summer day, but the scene was actually filmed in winter, and you can see the breaths of the characters in the air. See more