Since Iván Zulueta does not belong to the union of filmmakers, was José Luis Borau who officially appeared as a director.
In that time in Spain, the ways in which someone could legally direct a movie was having an official card from the filmmakers union or having a degree in the Official Film School (Escuela Oficial de Cine, EOC). Director Iván Zulueta didn't have any of them, so producer José Luis Borau (who was already also a prestigious director) had to appear in ending credits as the director. In opening credits appears "Un dos tres... al escondite inglés, by Iván Zulueta".
The film premiered at Cannes Festival in 1969 but, because of hurdles with the authorities of the Franco dictatorship (due to the experimental nature of the movie), it was not officially released in Spain until 1970.
Without count José María Íñigo by his double character as Rosco and as himself, all the main characters are named as the actors who played them, or in a variation of their surnames, except Ramón Pons, who plays Gasset. This was because the character originally was going to be played by Antonio Gasset.