Instead of recording voice-overs in booths, with every actor isolated from everyone else, most of the voice-over work was recorded on a set, with the actors voicing their characters while performing with their fellow cast members. This enabled the performers to follow the rhythms of their co-stars, while also giving them room for improvisation. The same thing was done for Shark Tale (2004).
(at around 22 mins) At the poker table in the saloon when Rango first enters, there is an owl in a top hat holding a pair of black aces and a pair of black eights. These were the cards held by notorious Wild West gunman 'Wild Bill' Hickok, the moment he was shot dead in a saloon in Deadwood, South Dakota. Bill's hand is since known as "The Dead Man's Hand".
(at around 1h 26 mins) Clint Eastwood is the visual inspiration for Spirit of the West. In the back of his golf cart, the "Spirit" has five Oscar-like film awards (which Rango calls "golden guardians"). Eastwood has received exactly five Oscars, including his Irving J. Thalberg Award. The voice of the "Spirit," Timothy Olyphant, starred in the Western television series, Deadwood (2004).
(at around 9 mins) In the beginning of the film, Rango lands on the windshield of a red convertible in the desert. The driver, car, passenger, and location all are modeled after Johnny Depp's portrayal of Hunter S. Thompson/Raoul Duke in Fear and Loathing in Las Vegas (1998).
The voice actors were given Wild West costumes to help them break into character.