Colbert, opening his second program on Wednesday night, said that a combination of an overstuffed show that needed to be edited and a technical glitch temporarily prevented producers from sending the finished product to the network.
"At 11:20 -- and this actually happened -- no one in the building could give me a guarantee that the show was going to be on the air," he said. The show airs at 11:35 p.m. ET.
"You could imagine how exciting that was for all of us, after CBS had plastered my face on every flat surface on the planet," he said.
The problems were corrected just in time.
"As I felt the oxygen begin to drain from my brain and all of my organs shutting down, I thought if we actually made it to air, this will be a pretty good story," he said. "And if we don't, it will still be a good story at the theater camp I will be running in Idaho."
Good thing for CBS that it was fixed, because viewers were curious. Colbert's debut averaged 6.6 million viewers, more than double what Jimmy Fallon had on NBC's "Tonight Show," according to the Nielsen company. The two shows appeared to be much closer in viewership the second night, early estimates indicated.
Actress Scarlett Johansson was Colbert's guest, the second straight night he featured a celebrity who also played a prominent role in predecessor David Letterman's final run of shows. George Clooney was on the night before.
On Wednesday, Colbert also sat down with Elon Musk, CEO of electric car company Tesla Motors.