Connecting a single wire to one single pole of a battery does absolutely nothing at all.
In the "shark chasing the boat" scene, the boat driver tells the others that they're streaming the event for more than 3 millions of viewers: this while the stream source, a tablet, is most of the time leaning on the boat desk showing nothing and with supposedly low to no internet connection due to them being in the middle of the sea.
2 to 3 millions of viewers is also an absurdly high number especially for an unplanned amateur random event stream.
The Atomic Shark sets on fire or fuses everything that is near it when it is outside of the water (for absolutely no reason) but no sign of this "property" is to be seen when it is in the water itself.
The final atomic explosion has no sense at all since no source for it could be contained inside such a small animal, even if radioactive.
Oxygen tanks are not so compressed to behave as shown multiple times throughout the movie.