At the beginning, Joe and a deckhand are shown diving down to see if there is any visible gold on the ocean floor. They are shown to be wearing wetsuits that leave a lot of their face and their legs from the knee down exposed to the water. In the Bering Strait ocean temperatures average between 27 and 41 degrees Fahrenheit. Both of the divers would be suffering from hyperthermia within minutes. Experienced divers would know to wear enclosed drysuits which would not expose their bodies to the cold in such conditions.
The first diving scene early in the movie is set well out to sea but the reflection of a dock and wharfs are clearly visible on the water's surface.
Donna, Joe, Owen & Megan crawl under an excavator to hide. When the creature comes in for a landing, the attached wire is visible for a few seconds before it is digitally erased.