With 7:35 left in a scoreless first period, Bishop, a finalist for the Vezina Trophy as the league's top goaltender, was scrambling around the Tampa Bay net during a Pittsburgh Penguins forecheck and seemed to tweak his left side or knee as he fell to the ice. Bishop immediately grabbed at his left knee.
It did not appear from replays as though any other players came in contact with him.
Trainers attended to Bishop, and even though he sat up, team trainers called for a stretcher, and he was taken from the ice. Bishop, 29, was replaced by backup Andrei Vasilevskiy.
Letang left the ice but returned to the bench during the injury timeout when Bishop was being attended to. Callahan remained in the game but is likely to face supplemental discipline from the league's Department of Player Safety for the hit.
Lightning center Tyler Johnson went down later in the first period on a hit into the boards. He appeared to suffer a lower body injury and had to be helped off the ice.