When Judy Hopps needs to run a plate to find the missing Emmitt Otterton, she blackmails Nick Wilde to do so as she's unable to complete the task herself, on account of being new to the city. To annoy and waste her time, Nick takes her to Flash, and sadistically prolongs the meeting by telling a joke, which Flash takes a while to react to.
At the end of the film, it is revealed that Flash also has a liking for street racing, driving a fast and fancy sports car, before he is finally caught by Judy and Nick, the latter now the former's partner.
During the end credits, he and Priscilla are seen dancing in a slow manner at Gazelle's concert.
In promotion for the film, a puppet version of Flash appeared in a video where he visited the El Capitan theater to watch Zootopia. The puppet was both voiced and controlled by Persi.
An emoticon version of Flash appeared in the Zootopia entry of the As Told by Emoji short series. His first scene was a joking reference to the occasionally long loading times of smart phones. He also appears after the credits, prolonging the arrival of the "The End" banner.
Flash uses a touch-screen computer because a sloth would never be fast enough to be able to double-click with a mouse.
Flash and Nick went to high school together and were both members of the track team. It was there that Flash got his nickname due to his love of drag racing.
Ironically, Flash's license plate is "FST NML" ("fast animal" minus the vowels).
In a Korean trailer, Flash drives a race car because he cannot get off the subway.
Flash owns a white coffee mug that says "You Want It When?".
At one point in the film's development, Flash and Priscilla were a married couple.
According to the Zootopia: The Essential Guide, one of Flash's hobbies is watching trees grow.
Flash suddenly turning into a speed freak isn't an out-of-character moment. In real life, three-toed sloths, presumably what Flash supposed to be, can actually be fast if angry or excited, meaning Flash is quicker once he raced in his car. Even if that's not the case, Flash is riding a race car, which is meant to be fast, and once Flash ride it, he has problems reacting to slow down his car.