Other mistake: In the early scene where the submarine has surfaced, titanosaurus emerges from the water and seems to be standing on the ocean floor. Just a few minutes earlier, the sub was at a depth of 250 meters, ergo the dino has to be walking on water.
Terror of Mechagodzilla (1975)
1 other mistake - chronological order
Directed by: Ishirô Honda
Starring: Akihiko Hirata, Katsuhiko Sasaki, Katsumasa Uchida, Tomoko Ai
Revealing mistake: In one scene, Titanosaurous bites Godzilla's lip and hurls him up in the air. It's quite obvious that there's no actor inside the suit, as it is much too skinny.
Katsura Mafune: Please kill me! Destroy my body! Inside me is the controller! Mechagodzilla's brain's installed in my stomach!