The Alexander the Greater Affair (1) - S2-E1
Character mistake: When Alexander organizes the human chess game in his courtyard, the "pieces" stand the wrong way on the board, with a dark square in the lower right hand corner. That corner is always a light square. (00:22:50)
Character mistake: Captain Crane has Bentley collared and is questioning him. An alive Lee Crane asks Bentley "why did you kill me?" He quickly changes it to "why did you try to kill me?" (00:10:40)
Character mistake: During the television report about the Sun Probe, a diagram shows the solarnauts' control cabin within the Probe Module. But we later see that the control cabin is within the body of the Probe Rocket when the Module is fired into the solar prominence.
Don't Bug the Mosquitoes - S2-E12
Character mistake: When the "Honey Bees" (Mary Ann, Ginger, Mrs. Howell) perform, Mrs. Howell (Natalie Schafer) messes up her lip-syncing throughout the number. But it is most noticeable at the very end when the girls put their heads together and say "buzzzzzzzzzzz" but Mrs. Howell is mouthing an "oooooooooo" which she changes to a "zzzzz" mid-way through the note.
Adam, Warlock or Washout? - S8-E14
Character mistake: In Season 3, Witches and Warlocks are My Favorite Things, Maurice says he won't stay for Tabitha's testing coven because it's "women's work" but in this episode, when Adam is finally tested, he arrives and says he wouldn't miss seeing his grandchild being tested.
Character mistake: When we first meet Gadus, he pronounces his name "Gay-dus", but later on in the episode Maran calls him "Gad-us".