Remake of the Italian movie "Perfetti sconosciuti".
Álex de la Iglesia decided to cast Belén Rueda and Eduard Fernández as a couple after seeing how well they worked comically in La noche que mi madre mató a mi padre (2016).
For one of the couples, Álex de la Iglesia wanted a real-life actors couple, so that's why he cast Juana Acosta and Ernesto Alterio.
Beatriz Olivares was actually 29 when she played 16-17 years old Sofía. Dafne Fernández (Blanca) plays a friend of Olivares' parents and is only 2 years older than her.
Very rare for an Álex de la Iglesia movie, almost all of the cast is working with him for the first time.