Moen suffered a laceration to his face 10:41 into the second when he was struck there by the blade of Cullen's skate after the Senators forward was upended along the boards in the left corner of Ottawa's zone.
"I had no idea -- I just turned and saw him on the ice," Cullen said. "Oh, that's really scary. It leaves you with a sick feeling in your stomach, of course, and I certainly hope that he's OK."
Moen, who doesn't wear a visor, was trailing blood as he was rushed off the ice with trainer Graham Rynbend. Moen did not return.
"It's scary when the skate comes up like that," Montreal defenseman Hal Gill said. "You just hope it's not the eye. You hope he's doing all right."
A Canadiens spokesman said that Moen was not expected to need to go to a hospital for any further medical attention.
Information from The Associated Press contributed to this report.