The Rangers were coming at the Flyers relentlessly in the second period and testing Mason non-stop. He just wasn't getting any help from his teammates, in particular his defensemen. Every few seconds the Rangers had another golden chance.
So he was forced to take it upon himself to keep the game from being a blowout and he did just that. Here's just a sampling of the types of saves Mason was making through the first 40 (via @PeteBlackburn).
Mason could only do so much as the Rangers carved up the Flyers defense to get two shots off that Mason couldn't stop. We're pretty sure that if Mason had free reign to scream every obscentiy at his defensemen during the intermission.