Fringe:” Season 3 Episode 10”

• Courtesy of Fox
• “BACK TO THE WHERE, NOW?” Christopher Lloyd as Roscoe Joyce

As if in celebration of its new, ominous timeslot, “Fringe” delivers an episode unusually rich in pop references. The title alone, “The Firefly,” shouts out to Joss Whedon’s “Firefly,” another sci-fi show with a cult following that couldn’t survive 9 p.m. on Fox Friday nights. It’s not just a nod to the Browncoats, however, since the firefly imagery in the episode harks back to the cliché of the butterfly effect, in which a butterfly flapping its wings on one continent can set off a hurricane on another. Not to get ahead of myself.

Music bookends the episode, with a cheerful Walter initially listening to “Mahna Mahna,” a beloved ditty best known here from its connection to Jim Henson. At the end, he’s in a state of melancholy, listening to a slow, jazzy arrangement of The Wizard of Oz’s “If I Only Had a Brain,” which might be a little too on-the-nose about his difficulties restoring his grey matter. During the hypnotherapy session with Roscoe Joyce, Walter dons red and blue-tinted glasses, which he ascribes to his colleague “Dr. Jacoby of Washington State,” a shout-out to Russ Tamblyn’s off-kilter psychiatrist from “Twin Peaks.” The line “When the time comes, give him the keys and save the girl” to me sounds like a self-conscious echo of “Heroes’” “Save the cheerleader, save the world.”

Casting Christopher Lloyd as aging musician Roscoe Joyce has its own meta-implications. Lloyd evokes all kinds of geek media history, from “Taxi” to Star Trek III to The Addams Family movies, but his presence may wink to the Back to the Future trilogy, especially since the episode harks back again to the events of 1985 — the year of the first film’s release. (And we already know that Eric Stoltz starred in Back to the Future in the alternate universe.) I’m not sure about the implications of Joyce’s band name, “Violet Sedan Chair,” but am open to suggestions.