The Quadripartite Affair - S1-E3
Plot hole: Solo blows open the ceiling vent of Illya and Marion's cell, and she stands on Illya's shoulders until Solo can reach her and pull her out. This leaves Illya with nothing/no one to stand on, no way to reach the vent and no apparent way out of the cell. But he's out just the same in the next scene, with no explanation as to how. (00:42:40)
Plot hole: The Seaview's crew have a wild shootout aboard ship, and their bullets are seen to go all the way through a 6-inch-thick hatch door. Gee, you'd think that somewhere during their military training, somebody would have taught these guys why firing high velocity weapons on a submerged submarine is a really bad idea. (00:38:15)
Plot hole: Dr. Quest is speaking through the Dragonfly's speakers to the Po-Hos as they fly over the jungle, telling them he is their air God and is angry the tribe has taken hostages. Quest could have told the Po-Hos to just release the hostages, rather than putting himself in danger later on by getting captured.