The "Wild Brood" (a gang of bikers that look like Orcs) comes to town. Daphne and Velma hang out with them for a while. When the Crystal Cove Armory is broken into and a rocket launcher is stolen, the bikers are suspected.
This episode originally aired March 15, 2011 on Canada's Teletoon
The episode's title "The Wild Brood" is a parody of The Wild One starring Marlon Brando.
All of the Wild Brood names are something meaningful backwards. Odnarb is "Brando" and he talks like Marlon Brando. The others are all words like "dork" and "goof."
The name of the episode could also be a play on The Wild Bunch, a 1969 western about a gang of outlaws, but the parallels to the Brando movie are much stronger.
The runaway train scene appears to be a parody of the train scene on Back to the Future III (1990); the scene of the runaway locomotive derailing off the damaged trestle and graphically exploding among impact resembles the train explosion from the same movie.