Bruno Mars was so busy hosting and playing musical guest on the same episode of “Saturday Night Live,” Tom Hanks was enlisted to introduce his performance at one point.

The indispensible Hanks hung around to mop up in a few other skits, as a Long Island resident in the reliably uproarious takeoff of the second presidential debate that opened the show, as a lecherous robot in a mechanical haunted house as well.

But Mars was plenty busy, appearing in most skits and getting to sing a lot. He took to song to express his nervousness at hosting in the monologue; then portrayed a lowly Pandora employee enlisted to fill in for pop voices from Green Day to Aerosmith to Bieber to Michael Jackson in another sketch. He dawned a dress for a skit about a daytime talkshow called “Haters” and did the robot in the haunted house skit, and was desk clerk in one about a cabin near Bigfoot.

In all of them, the sketches weren’t much, and didn’t have endings, but Mars was pretty solid in all that he was asked to do.

The debate sketch pretty much wrote itself, with writers homing in a little meanly on specific Long Island questioners with their heavy accents and odd hairstyles. The byplay of Jason Sudeikis’ Romney and Jay Pharoah’s Obama was that they were about to break out into a fight. The debate was a chance for newcomer Aidy Bryant to have her longest sketch appearance yet, appearing as moderator Candy Crowley.

Sudeikis was all over this episode, in just about every sketch, making you wonder who will step up when he steps down following the election.

“Weekend Update” was dominated by the character Stefon, with Bill Hader cracking up a little too much at the lines. Proving his popularity, though, it was Stefon in character who introduced Mars’ second musical performances.

It will be interesting to see what Louis C.K. gets to do as host of the next live show Nov. 3.