While in the underwater cage, one signals the "thumbs up" sign to mean "OK". Thumbs up in scuba diving is a sign to return to the surface, and would be confusing and potentially dangerous in real life. OK is done making a O with your thumb and forefinger.
It's been noted that in the shark cage Jack incorrectly signals an excited "Yes!" to Tim by giving the "thumbs up" sign, which to scuba divers means something quite different, but since both are business executives and not trained divers, they would naturally signal as naïve executives and not skilled divers.
At one point Missy dips her hair in wine, in the next scene it is dry.