At approximately 55 minutes, the young woman "Mango" is discovered coming out of the jungle, and again 5 seconds later.
When the monster attacks the ship at the end of the movie, you can see human skin where the costume sleeves didn't reach the gloves.
The creature may have risen from the slime and moss of the ocean floor but he sports a nice pair of rubber swim fins.
At about 16 minutes into the movie when Marry Belle is insulting the Cuban generals, the subtitles misspell the word "carriage" as "carraige".
Almost at the end of the movie, when the "monster" is manipulating the box under water, the driver's mask and regulator can be seen where the creature's neck should be.
When they are on the island near Puerto Rico, one of the crew comes back with a pineapple. Pineapples are not grown in Puerto Rico, but in Hawaii.