When Willy puts on his wetsuit hood the bottom is loose. To be effective a hood has to be under the wetsuit jacket to help keep cold water from easily getting under the flap.
When Barney unscrews from the inside the container side from the compressor crate that Wiley delivers, as it drops there is no attachment nuts for the bolts to be secured to.
The underwater scene was filmed in an aquarium. The viewing windows are obvious in the background.
In the opening scene the diver tapes the bomb to the boat's windshield with thick black tape. When the boat heads towards the camera just before it explodes the windshield is empty.
The presented underwater operation of retrieval heavily depends on radio communication. The radio waves however don't propagate in water in usable quantities. It is unlikely even for XXI century equipment to maintain radio communication or tracking in water with such tiny earpieces.
In the final scene instead of driving off into the sunset, Barney drives over the curb.