This episode is considered non-canon, and the events featured are not part of the timeline of the series' continuity.
Thanksgiving of Horror is the eighth episode for Season 31.
Synopsis
In a special Thanksgiving edition of "Treehouse of Horror," The Simpsons are forced to face various Thanksgiving nightmares, including the first Thanksgiving, an A.I. mishap and a dangerous space mission complicated by a sentient cranberry sauce.