Chal Pivik was in the studio audience for the taping and writes:

Conan O’Brien fell during the taping of his show today at Universal Studios, hitting the back of his head as he was performing a skit with guest Terri Hatcher. O’Brien walked off the set, returned, then left again. A  short while later, announcer Andy Richter announced that the remainder of the taping was being canceled, saying Conan was “up and walking around” but was going to see a doctor “just to be sure he’s okay.”