Initially Leslie Nielsen was only hired to appear in the teaser trailer, pitched against Spanish comedian Chiquito de la Calzada to show the contrast between American and Spanish humor. However, when the teaser came out hype was created about seeing Nielsen in a Spanish movie, so he was re-hired to shoot a part in the actual film.
The crew was given a number of strict conditions before working with Leslie Nielsen on account of his deafness and advanced age, including that he should always go to bed before midnight. Director Javier Ruiz Caldera joked that the experience was like working "with a gremlin".
The bank security camera film showing Maligna disguised as Espinete with a fake beard is a parody of a security camera film showing Jaime Giménez Arbe aka "El Solitario", reputed to be Spain's most dangerous bank robber, who also used disguises including a fake beard. "El Solitario" committed over 30 bank robberies between 1993 and his arrest in 2007, mostly in rural areas.