NBC Nightly News anchor Brian Williams left the real 30 Rock today to film a scene of the TV show “30 Rock.”

Insiders tell us Williams was at the studios of NY1, which was supposed to be the studios of CNBC. But NY1 is on the west side of Manhattan, while the real CNBC is all the way in New Jersey. Enough said. (Image Courtesy: NY1 reporter Bree Driscoll).

Williams has been in two prior episodes of the NBC show.

NBC Newsman Brian Williams during a “30 Rock” episode from earlier this season.

• More: Gawker has a Twitpic of Alec Baldwin and NY1 anchor Pat Kiernan during today’s filming.