The episode carries production number 75007 and is episode five in both air-date and DVD order, appearing on Vol. 1, Disc 1 of the DVD release.2 It was recorded on June 17, 1986.2 As with the rest of the first season, the score draws on the show's soundtrack album; "Troll Bridge" uses the song "Party On His Mind" in two places.
The original recording featured Lorenzo Music as Peter Venkman and Laura Summer as Janine Melnitz, alongside regular cast members Frank Welker, Maurice LaMarche, and Arsenio Hall. Guest voices were provided by Sheryl Bernstein and William E. Martin.
This is one of seven early-season episodes later re-dubbed with Dave Coulier and Kath Soucie replacing Music and Summer. The redub was rebroadcast as part of the fourth season and was not included on the DVD release.
Flem Nachman also appears in the episode as a human supporting character.
The principal supernatural threats in this episode are the Trolls occupying the Queensboro Bridge and their Fireflies. The trolls depicted are bridge-dwelling creatures catalogued in Tobin's Spirit Guide. The episode's main troll group falls into the category of common trolls, while Egon demonstrates the ability to speak their language. The rogue troll who flees into the city is benign, seeking only to dance and socialize rather than cause harm.
The Fireflies are paranormal entities deployed by the troll leader as an offensive weapon when his ultimatum is not met. The Ghostbusters find their particle throwers ineffective against the Fireflies; the entities are ultimately dispersed by flooding them with water drawn from a manhole and a rooftop water tower. No further appearances of Fireflies are recorded in the series.
Club Kat is the Times Square nightclub where the runaway troll is eventually found. He enters incognito and wins the admiration of other patrons with his dance moves before the Ghostbusters locate him.
A lone troll sneaks away through the sewers, dodging his comrades, and climbs out of a manhole to hide in a trash can. After some garbage is dumped on him, he emerges wearing clothes, watches a group of street dancers, and happily imitates them.
The next day, a truck stalls on the Queensboro Bridge as several trolls appear. At the firehouse, Peter wakes up to find Slimer has slimed him. The alarm sounds, and a news flash reports the bridge has been seized with no demands issued. Egon is intrigued that the culprits are trolls and briefs the team on the creatures from a copy of Tobin's Spirit Guide on the way over. Peter is volunteered to make contact; Egon warns that their proton streams might turn trolls to stone or only make them bigger and meaner. The troll leader emerges from a car and eats Peter's white flag. Egon speaks to the leader in the trolls' own language and learns they have lost a member of their group and want him back. The leader issues an ultimatum: return their friend within twelve hours, or he will send fireflies to destroy the city.
Peter and Egon check the Holland Tunnel while Ray and Winston search Times Square. With less than an hour left, the leader targets the Empire State Building. Ray realizes the runaway troll is drawn to music, and the team heads to Club Kat. The leader unleashes the fireflies and drives off in a monster truck. The Ghostbusters' throwers prove useless against the fireflies, so they disperse them with water from a manhole and a water tower. Out of time, the team ducks into a lawn decoration store and pays the owner to produce a troll statue. Peter pretends they were forced to fire and turned the runaway to stone. The leader believes him and sadly carries the statue away. The Ghostbusters then ship the still-living troll off by train to one of Peter's partying friends in Chicago, who owed Peter five dollars anyway.
Peter Venkman: Me Dr. Venkman. You...troll. What's the problem?
Marsha Goodman (1986). Episode Call Sheet and SAG Report, "Troll Bridge" (1986).
The Real Ghostbusters: Sticker Collector's Album (Diamond Publishing Inc.), featuring "Troll Bridge" and "Mr. Sandman, Dream Me a Dream."