Finn's look started out "pretty bland, like the nerdy character Brad is," says costume designer Lou Eyrich. But once Cory Monteith put on the black-rimmed glasses and got a side part in his hair, he transformed. "Cory's just a big goofy nerd and so is Brad," says Colfer. "He was perfect."

When Puck drops out of the production, John Stamos' Dr. Carl fills in — crashing his motorcycle through a stage wall. Since it's difficult to imagine hunky John mimicking a role played in the film by Meat Loaf, Carl does "his own sexy version of Eddie to intimidate Will [Matthew Morrison]," says Eyrich. "It was actually John's idea to do a take-off on Elvis' leather-suit look from his 1968 TV special."

"Here, Quinn [Dianna Agron] is one of the partygoers for our big 'Time Warp' dance scene," says Eyrich. "When the hairstylists told us they wanted to give Dianna a pink wig, we gave her a pink top and glittery hat. To make it more youthful, we used a high-waisted pant from H&M and a gold cummerbund." Quinn does double duty in the production, joining Santana (Naya Rivera) as dual versions of kinky-wigged domestic Magenta.

"At first, Sam [Chord Overstreet] is wearing tiny little gold shorts, but then they decide that's maybe not appropriate for a school play, so he ends up in these gold board shorts and tank top," explains Eyrich. Overstreet was shocked when he saw what little he'd be wearing. "He was a really good sport but hit the gym extra hard," adds Eyrich. But Colfer has no sympathy: "Ha! Take that, new guy!" Glee Rocky Horror Picture Show

"Riff Raff is the best character, and everyone was amazed at how incredible the makeup was," says Colfer. "I was mistaken for a blonde woman a couple times. All I kept thinking was, 'You did this to yourself, Chris.'"