(Warning Possible Spoilers) There are a lot of things to be said about this episode, and all of them are good. First of all, this episode, like the other episodes this season, uses the monster/killer of the week to advance the overall mythology of the show, which has proven to be very effective. In this case, we start with the "Candy Man," an aged (and masked) serial killer from the other side who sucks the pituitary glands of children to retain his youth. Also, Candy Man secretes some kind of a sugar/sucrose from his body, which is where his nickname comes from. As a kind of evil robin hood, Candy Man provides some of the pituitary youth serum to his local church, which in turn, heals the sick and faithful.
Colonel Broyles' son was among Candy Man's victims several years ago. As a result, Broyles, like Walternate, takes kidnapping cases very seriously and also helps us (the viewers) sympathize/empathize with the characters "over there." One of the things that I've loved about this season are the little differences between the other side and the regular universe and the contrast between our Olivia and her counterpart. In today's episode for example, we learn that there's a place called New Yonkers. (Whatever happened to the old Yonkers?). The FBI was disbanded ten years ago. (Olivia accidentally tells one of the child victims that she's part of the FBI, and he doesn't know what that is. Olivia replies that it's another word for "police." Broyles later tells Olivia that the FBI doesn't exist on this side... at least not anymore. It was disbanded - why, we don't know. Maybe Fringe Division has assumed that role or maybe it was subsumed in some other agency.) Meanwhile, Alternate Olivia is watching Casablanca. Although she said she has heard of the title, she seems unfamiliar with the story or with Humphrey Bogart, who she thinks is "Ronald Reagan." Perhaps Casablanca exists over there, or perhaps it's a completely different story. That's one of the great things about the alternate universe.
Other stuff: Olivia tells Lincoln that she has worked on a case like this before, where the bad guy sucked fluids out of people's pituitary glands to reverse the aging process. Lincoln stares at her and says something to the effect of, "When was this," to which Olivia replies, "before I joined Fringe division." What was the alternate Olivia doing before she joined Fringe division? I think Lincoln knows (or suspects) that this isn't his Olivia, just like alternate Charlies does/did.
Final thoughts: Andre Royo returns as Henry the cab driver... hooray, and Peter makes a long-awaited discovery.