In the film, the Toon Patrol are the law officers of Toontown, but they behave more like vigilantes and mercenaries. Judge Doom has hired them to arrest Roger Rabbit for the murder of Marvin Acme. The Toon Patrol drive around in a 1937 black Dodge Humpback paddy wagon.
The weasels enjoy laughing at the misery of others, including each other. Like all the other Toons in the movie, they are invincible to physical body harm (except the Dip); however, prolonged laughter is shown to be lethal to them. Eddie Valiant jokes around in front of them during the climax of the movie, causing all but Smarty to "die" from laughing at him, after which their toon souls rise to heaven in angel forms. According to Judge Doom, they once had hyena cousins who died in the same manner (although in real life, hyenas and weasels are from different animal families).
[While being designed, the weasels and their fondness of weapons were modeled after the weasels in The Adventures of Ichabod and Mr Toad. The weasels make an appearance in the Roger Rabbit's Car Toon Spin ride at Disneyland Resort.
- Smartass (Wise Guy in Roger Rabbit's Car Toon Spin), voiced by David Lander, is the smart, wisecracking leader of the weasels, and ranked a sergeant by Judge Doom. He has brown fur and wears a light pink double breasted zoot suit coat with a gold chain in the left pocket, a white dress shirt with a reddish pink, bejewelled tie]], a matching pink zoot hat with a darker pink band, and spats on his feet. His weapon of choice is a revolver, though in the bar scene he is shown threatening Eddie Valiant with a switchblade. He is a frequent committer of malaprops. Smarty proves to be the most disciplined of the weasels, as he has more control over his laughter and tries to get his cohorts to follow suit. He is the third weasel to die in the film, but not by losing control of his laughter. After he disagrees with a lyric Eddie "entertains" the weasels with, Eddie kicks him in the crotch, sending him into the reservoir of Judge Doom's Dip sprayer. Unlike the others, his angel does not appear after his death (presumably the Dip dissolved that too).
- Greasy, voiced by Charles Fleischer, is Mexican, and has long greasy black hair and dark brown fur. He wears a green zoot suit styled trench coat and trousers hiked up all the way to his chest, a partially obscured pink tie and white dress shirt, as well as a tall green zoot hat and spectator shoes, and is overweight. His weapon of choice is a switchblade knife, although at one one point in Eddie Valiant's apartment, he is seen wielding a revolver. He is mostly shown speaking English with a heavy accent, and curses in Spanish when Roger shoots into the Acme Factory via a storm drain, propelling Greasy and himself up towards the ceiling, and when he springs a bear trap hidden in the top of Jessica Rabbit's dress. He also appears perverted, as he quickly takes Judge Doom's orders to search Jessica for Acme's will as an opportunity to feel her. He is the fourth weasel to die after losing control of his laughter, and drops dead out of the cab of the Dip Machine, putting in gear as he does so.
- Psycho, voiced by Charles Fleischer, is the most mentally unstable of the group of weasels. He has a shrilling laugh and high-pitched voice. Psycho wears an unbuckled straitjacket, has a lighter, tanner muzzle, blue eyes with yellow and white swirls characterizing his insanity, and unkempt fur by the hairline, giving it a spiky appearance. His weapon of choice is a barbershop straight razor. He is the last weasel to die, laughing hard enough to lose his balance and fall into the machinery of the Dip sprayer. As his soul rises to heaven, it throws a lever on the machine before the sleeves of his straitjacket buckle themselves together, showing that even after his death, he was still dangerous.
- Stupid, voiced by Fred Newman, is the dumbest of the weasels, though he appears to be more childish than unintelligent. He wears a horizontally striped blue and white t-shirt, a red beanie with a propeller on top, and white tennis shoes that are constantly untied. He has a pigeon-toed stance, and his weapon of choice is a baseball bat with a nail in it. He is also very fat. Stupid has only one line in the film "Ehh, Toontown's right on the other side of the wall, boss!". He is the first weasel to die after losing control of his laughter, knocking himself over the head several times before keeling over and his hands were seen clutching a lily.
- Wheezy, voiced by June Foray, is a heavy smoker. Unlike his compatriots, who all have brown fur, his fur is smoky blue and has long, nicotine-stained fingers. He is dressed in a wrinkled dress shirt, black vest, pork pie hat with cigarettes stuffed into the band, and loose black tie, all of which are stained to some degree from nicotine. His weapon of choice is a 1940's Tommy gun, though he only uses it once, when he was searching Eddie Valiant's office. When he has cigarettes in his mouth, he has a harsh, raspy voice and when he doesn't, he has a deep voice, as shown when he says "Let's go!" after Eddie Valiant and Roger Rabbit free Benny the Cab. Wheezy is the second weasel to die, as his soul escapes while he is hanging from a ladder; he tries to pull it back but to no avail. Wheezy was at once though to be female, since he was voiced by a woman.
Other weasel names considered but dropped during production were Slimy and Flasher (who were designed), as well as Crazy, Sleazy, Scummy and Twitchy (who were not).