Tree House of Horror XI - S12-E1
Continuity mistake: In Reaper madness, there's a scene which Homer wakes up being the grim reaper, he puts the robe on at which point he is wearing a singlet. In the next scene where God turns Homer back to his regular self he is wearing his white shirt.
Tree House of Horror XI - S12-E1
Continuity mistake: In the "Scary Tales can Come True" segment, Bart's plague rat bite disappears for the rest of the segment.