Deliberate mistake: "The Creature's Revenge" (Adventure 3, Part 5): The 2-inch heels on Sapphire's bright blue boots disappear and reappear repeatedly. They're most often missing in the scenes she appears in with Steel, presumably so that her height won't exceed his. (00:15:15)
Plot hole: White Base and the interior of Luna II withstand without a scratch the explosion of the thermonuclear reactor from the Magellan from just a few meters, while the blast literally vaporizes the Zaku far away from the entrance and threatens to damage the Musai, hundreds of meters away.
Return of the Fighting 69th - S1-E6
Revealing mistake: Before Roxanne Trent hits the box, it is possible to see that her hand is normal, not iron. (00:17:01)