During his monologue, Taran Killam and Bobby Moynihan interrupted him to ask him to play "Batman" and "Beetlejuice" with them.
The 63-year-old actor turned down the two's requests, but Killam and Moynihan edited footage of Keaton backstage on the show to fulfill their dreams.
Keaton eventually delivered one-liners from Killam and Moynihan's favorite movies at the end of the monologue, reported Ace Showbiz.
In one of the sketches, Keaton played a teacher whom Mike O'Brien's high school student's character asked to the prom as he made a bet with a friend that he could make anyone who went with him a prom queen.
Meanwhile, "SNL" parodied Scientology in a music video from fake group, a science-based religion Neurotology. The show also poked fun at CNN and its excessive use of reenactment videos with Cecily Strong playing anchor Brooke Baldwin. Responding to the skit, Baldwin called it "a crazy compliment" on Twitter.