Starring: Tara Strong, Dee Bradley Baker, Paul Eiding, Meagan Smith
Back With a Vengeance - S2-E13
Plot hole: It is rather strange that grandpa Max would have a kid-sized Plumber suit ready for Gwen, given a) that the Plumbers are effectively defunct, and b) that a government organization would hardly allow underage trainees in their ranks.
Be Afraid of the Dark (2) - S3-E12
Plot hole: When the Corrodium Beam is shut down, there is a brief scene of the sky clearing at Mount Rushmore. But on the cliff face all four heads are seen, whereas the head of Theodore Roosevelt got crumbled in "Secrets," and it's too far forward to have been carved into the mountain face, in place (and same position) of the old head, yet again.
Grandpa Max Tennyson: Being a hero isn't about letting others know you did the right thing, it's about you knowing you did the right thing.
Ben Tennyson: What were you just doing, reading greeting cards back at the Mega Mart?
Grandpa Max Tennyson: Well... yes.
Trivia: 4-9 "Ben 10 vs The Negative 10 I": The holiday camp where Cooper is picked up by Max Tennyson looks quite like Camp Opinicon from season 2's "Camp Fear".