Revealing mistake: When Lily throws the ticking apple bomb out of the ship's portal and it explodes, it is dark outside as the scene takes place at night. Stock footage of a depth charge explosion shows daylight.
Revealing mistake: The stuntman playing Grandpa is obvious when Herman jumps into his arms after scaring the two guys carrying the coffin.
Revealing mistake: Al Lewis and Yvonne DeCarlo's stunt doubles are obvious when Grandpa and Lily mount the horses.
Revealing mistake: The wires used to lift Lady Effigie's chair as Herman lifts the chair to kiss her are visible.
Revealing mistake: Actress Yvonne deCarlo's palms and insides of her fingers do not have her green makeup applied like on her face, arms, etc.
Revealing mistake: The horses shown in close up that Lily and Grandpa are riding are obviously fake.
Revealing mistake: A safety wire is visible as Grandpa hits the low tree branch that knocks him off his horse.