The 53-year-old actor is welcomed back to the sketch comedy show by cast member Taran Killam, only for a battle to the death to begin, reported Deadline.
Killam also finds himself confused by just which Harrelson will be appearing on SNL this weekend.
Harrelson is hosting 'Saturday Night Live' for the third time, making his return after a 22-year absence.
The actor first guest hosted the landmark sketch comedy series on November 18, 1989.
His musical guest will be Kendrick Lamar.