The so-called unmanned submarine that was destroyed during the torpedo demonstration was clearly based on the USS Triton, a U.S. nuclear-powered submarine that was famous for making the first submerged around-the-world voyage in 1960.
At 51:18 Dr. Howard turns to reporter Ken Abe, and says "Don't worry Dr. Abe..." . "Dr. Abe" should be "Mr. Abe".
At 1:07:13 as one of the creatures falls over backwards, his right knee tears through his costume and his human skin appears.