You can see Jacket's tiger mask in the court room on an evidence table, then again, it could always be a spare that Tony got his hands on, who knows?
My guess (and the wiki's too) was that somehow he got the mask from the guy Jacket blows up in Tension, since he has a tiger mask that probably got messed up by the explosion, tony found it (again somehow cuz im sure that the cops might show up at the área were there was an explosion and start to investigate what happened) and has used it ever since.