Slave Island - S1-E7
Plot hole: After Storm's attempt to escape the Genoshan prison is thwarted, she ends up in the ocean right at the shoreline of the beach, where she is captured by a Sentinel. Aside from the fact that it makes no sense for a Sentinel to be hiding in the ocean in the event that a mutant tries to escape the prison, there is absolutely no way that a two-story tall robot could hide in the ocean right by the beach, as the water would be way too shallow. You can even see that the water level only goes up to the Sentinel's ankle area when it is standing upright in the ocean. (00:03:15)
Suggested correction: Perception. (1) The Sentinel isn't as close as it appears. If it were close, then she would have been caught in its waves as it emerges. Also, she would be looking only at its chest circle. It's several yards away. (2) She washes ashore. She fell from the sky. She couldn't have fallen from that great height into shallow water without hitting bottom. (3) It's also a two-story tall robot. Its weight would sink it into the sand. So it could have very well been down that deep.
Sentinel never sank into sand in other episodes.
Well, it's shown here.
Slave Island - S1-E7
Plot hole: When the Leader says "Take me to my car at once!", one of his guards goes to open the door to the room only to have Cable shoot the door with his plasma rifle. The Leader then says "The other way you fool!" and everyone in the room starts running for the windows that Cable shot out a few minutes earlier, which happened to be the only other way out of the room. As evidenced earlier from when Cable shot the windows out, that particular floor appears to be 8 stories up, so if everyone in the room exited through the windows, they would have all fallen to their deaths as all of them were regular humans with no superpowers. (00:17:40)