Pretty Little Liars: 6 Juicy Hints About the Finale, Straight From Huw Collins

"I think that there are a couple things that you can take from the reveal, and the fact that Dr. Rollins was wearing a mask. I think that it would be fair to say that, given the reveal, and given the fact that other characters have been wearing masks to masquerade as someone else, to gain information, or to further this overall plot. I think it would be fair to say there's a fairly high proportionate chance that Dr. Rollins has been masquerading as other people throughout the season. However, I would say that, on the flip side of that, it would definitely be dangerous to assume that, if he has been, he's been the only one doing it."