The Disney film referenced by the character name “Duke Weaselton” in Zootopia is Frozen.
Duke Weaselton is a small-time weasel criminal whom Judy Hopps chases after he steals flowers from a shop. His surname is a joke built around the Duke of Weselton, a scheming dignitary from Disney’s Frozen. In Frozen, the duke represents the neighboring territory of Weselton and becomes hostile toward Elsa after discovering her powers.
The reference is especially easy to miss because Duke Weaselton is not a crossover character and never mentions Frozen in Zootopia. The connection is a visual and verbal pun: “Weaselton” sounds like “Weselton,” while the character’s title echoes the duke’s title. Alan Tudyk voices both characters, adding another deliberate link between the two films.
A common mix-up is confusing Duke Weaselton with the Duke of Weselton himself. The former is a Zootopia criminal; the latter is a political antagonist in Frozen. The name also fits Zootopia’s broader habit of hiding Disney references in character names, locations, and background jokes.