Continuity mistake: Season 4, episode 10 "Ben 10 vs. The Negative 10, Part 2": When the Forever King makes his announcement "Nothing will stop this little home-coming", he stands outside the Mount Rushmore base on bare soil. But in the scene where Max reviews the recording of this speech, all of a sudden we find the Forever King standing on a neatly tiled floor.
Continuity mistake: When Miles jumps off the ferry to swim ashore, the camera view is from the ferry: he jumps into quiet, fairly level water, yet the camera recedes from him (he jumped off the back of the boat as the camera continues moving with the boat). The angle changes and we see the wake of the boat - but it's not what he jumped into.
Continuity mistake: As Dave is leaning over the edge of the air boat with Rose behind him, he pulls a chunk of metal out of the water and places it on the edge of the boat on his left side. When he gets up from his lying position moments later, the metal is gone. Moments later again, with an overhead shot of the boat, we see what appears to be that piece of metal positioned at what would have been his right side, not his left. This is also where we see him step over the seat (twice!) in subsequent camera angles. (00:30:00)
Soshite, ame wa furiyuku - S1-E4
Continuity mistake: When Wendy drags the unconscious Van uphill, the coat covers his shoulders less in close-up and more in the other shots. (00:05:05)