The $77 million send-off

The final episode of The Late Show with Stephen Colbert featured a 77-minute finale packed with celebrity cameos and a musical send-off led by Paul McCartney.

The show also included a running gag with celebrities thinking they were the final guest and a surreal segment with a wormhole and a snow globe.

Who's who of celebrity cameos

A who's who of celebrities turned up for a running gag, each showing up convinced they were the final guest and having hilarious reactions when they realized they weren't.

Actor Paul Rudd said he'd brought a long poem and the traditional retirement gift of six bananas (which promptly became five).

Comedian Tig Notaro quipped that she likes being at historic events like 'the Obama inauguration and the moon landing.'

Actor Ryan Reynolds, disappointed he wasn't the final guest, said he came to pay his respects, bringing bananas for house band keyboardist Corey Bernhard.

The wormhole that swallowed them all

Throughout the show, brief green blips appeared on the set, which revealed a so-called interdimensional wormhole.

Colbert confronted it with astrophysicist Neil deGrasse Tyson and playfully shoved deGrasse Tyson into the portal .

Other late-night colleagues — Jon Stewart, Andy Cohen, and the 'Strike Force Five': Jimmy Kimmel, Jimmy Fallon, John Oliver, and Seth Meyers — appeared in sketches about the wormhole eventually coming for all their shows.

A musical send-off and a snow globe

A montage then depicted the wormhole swallowing people and objects around the theatre, followed by a large musical send-off with McCartney leading.

Everyone sang, clapped, and embraced the 'joy machine' spirit Colbert invoked at the top of the show.

Colbert let McCartney shut down the lights of the Ed Sullivan Theater one last time.

In a surreal bit, the theatre was sucked into the wormhole, became a snow globe, and Colbert's dog Benny sniffed it — a whimsical sign-off that closed one chapter and hinteed at the next.