Sunday's Dave-Jay-Oprah Super Bowl ad [1] might have been a foursome -- but an early notion to include Conan O'Brien in the spot didn't work out.

Rob Burnett, executive producer of David Letterman's "Late Show," said he approached Team Coco about O'Brien appearing in the promo.

"There was an initial thought of having Dave, Jay and Conan together in the spot," Burnett told TheWrap. "I did call Jeff Ross (O'Brien's producer) to talk about it."

But the call came just as O'Brien and Ross were finishing up production on "The Tonight Show" -- and nothing ever came of the idea.

"It wasn't as if they even said no," Burnett said. "I just think they weren't in a position to consider it all."

Indeed, Burnett doesn't think O'Brien's reps even raised the issue with NBC, because it never came close to happening.

No matter. As shot, Sunday's promo emerged as an instant classic -- at least among media types obsessed with the drama of LateNightCrisis 2010.

Burnett said CBS let Letterman know a few months ago that it wanted to give him the chance to hype "Late Show" again in the Super Bowl, following 2007's successful Dave-Oprah spot.

"There's nothing more simultaneously exhilarating and fear-inducing than being told you have 10 seconds of time in the Super Bowl," Burnett said. It didn't help that the 2007 ad was so well-received.

"We figured, 'What could we do to possibly compete with that'," Burnett said.

Despite having months to think about idea, "We didn't really turn our attention to it until the last few weeks," Burnett said. "We didn't forget about it, but it was kind of in the back of our minds."

Letterman came up with the idea of having the late-night hosts appear together. After getting CBS Corp. leader Leslie Moonves to sign off  -- "He immediately said, 'Go for it. This is hilarious'," Burnett said -- Burnett reached out to Leno's long-time producer, Debbie Vickers, on Jan. 25.

Vickers went to Leno with the idea, and Leno then "called me back like 20 minutes later to see if we were serious," Burnett said.

Leno said yes to the idea right away, something that didn't surprise Burnett.

"Jay's a comedian," Burnett said. "If it wasn't funny, I might have had a lot more doubt about it. But he understood that this was funny."

The Leno camp got their bosses at NBC to sign off on the idea. NBC, per Burnett, not only approved, but let Leno take the NBC U jet to fly to New York on Feb. 2 to tape the spot. The network hastily decided to ditch the Feb. 2 edition of "The Jay Leno Show" [2] to give Leno time to make the trip.  

Despite the on-air drama between Dave and Jay, Burnett said the mood on the set during the roughly 30 minutes it took to produce the spot was not weird at all.

"There was nothing frosty or awkward about it," Burnett said. "These guys have known each other for a long time. I don't think either of them particularly care about these jokes that have been made."

It helped that both men had a "focus" for the time they were together. "They were trying to execute this joke," Burnett said. "So a lot of the conversation was about the spot."

(Also read: "CBS' Super Bowl Shocker.") [1]