Benito Pocino had to be dubbed by comedian and voice impersonator Carlos Latre due to his poor pronunciation. Pocino's real voice can be heard on the original theatrical trailers and the DVD extras.
This movie has the highest budget for digital special effects film in the history of Spanish cinema.
T.I.A. stands for "Técnicos de Investigación Aeroterráquea", Technicians of Aero-ground Investigation. 'TIA' is spanish for 'aunt', a joke on the U.N.C.L.E. series.
"DDT", the acronym of the "Depresor De Tropas" ("Army Depressive Gun"), was a comic magazine that was published in Spain for many years. Francisco Ibáñez and many other comic writers worked in it.
(at around 1h 14 mins) When Fredy Mazas leafs through Filemón's exercise book, a little drawing of a secret agent can be seen. It is "Anacleto", a comic character created by Vázquez, who worked with Francisco Ibáñez in the magazine "Pulgarcito".