Fallon, Timberlake joined by McCartney, Madonna, Bloomberg on 'SNL'

Paul McCartney, Madonna, Barry Gibb and Mayor Michael Bloomberg all joined host Jimmy Fallon and musical guest Justin Timberlake on this year's final "Saturday Night Live," helping create possibly the best-reviewed episode in years.

Former Beatle McCartney appeared after a fake-out by Fallon, who picked up a guitar "to sing with three of my friends": David Bowie, Bob Dylan and McCartney. Those singers, unfortunately, were stuck in the Lincoln Tunnel, Fallon explained, but the show must go on. He then launched into "Joy to the World" with on-target impressions of the other three -- until McCartney himself walked in, saying he'd beaten the traffic using a Citi Bike.

"Am I too late to sing a song?" the music legend asked. The two then performed a duet of "Have Yourself a Merry Little Christmas" -- after McCartney first offered a humorous snippet of Alvin and the Chipmunks' "The Chipmunk Song (Christmas Don't Be Late)," high-pitched voice and all.

Madonna's cameo came when she played herself as a celebrity guest in the recurring sketch "The Barry Gibb Talk Show," in which Fallon plays Bee Gees singer Barry Gibb and Timberlake his brother and bandmate Robin Gibb. The sketch was retired following Robin Gibb's death in 2012, but Barry Gibb himself appeared as the sketch ended, joining the faux brothers in song.

Bloomberg, also appearing as himself, told Seth Meyers on "Weekend Update" of his plans for the future: "I'll be fulfilling a lifelong dream of enjoying a small soda on a nonsmoking beach." He also said he has "applied to teach Spanish at a few universities but I'm told that my accent isn't quite bueno." He said he might run for president, or possibly become "pope or Naked Cowboy."

"SNL" returns Jan. 18 with host and musical guest Drake.