Callahan suffered the injury in a tussle with the Flyers' Max Talbot four minutes and 42 seconds into the final frame. The two players dropped the gloves after a stoppage in play, although very few punches were thrown.
Both Callahan and Talbot were assessed two-minute roughing minors instead of five-minute majors for fighting.
As the Rangers' captain went down to the ice, there was an immediate expression of pain on his face. Callahan immediately went to the dressing room and seemed to be favoring his left shoulder.
After the game, head coach John Tortorella didn't have an update on Callahan's status. The Rangers' bench boss wouldn't speculate on what exactly the injury is, as well as if -- or how much -- time Callahan would miss as a result.
In 14:22 of ice-time in the 2-1 victory, Callahan registered his second goal of the season (his second power play goal) and his first game-winner of the campaign.
In addition, the Rangers' captain recorded two shots on goal and delivered two hits.