The theatre play that María, María León's character, is preparing is Anton Chekhov's "The seagull". As a young aspiring actress she asks Javier, played by Javier Rey to help by reading the lines while travelling in the bus. In the story Maria will change Javier's name for Trigo, as the male character of Trigorin in "The seagull", also obsessed with writing everything in his notebook.
On the cafeteria at the road stop Maria points a TV-set to Javier showing her performance in a video-clip of Spanish music group Mecano, very successful in the 80s. Actress María León was digitally added to share the screen with Penélope Cruz who originally stars in the clip Mecano: La fuerza del destino (1989) which was her first public appearance on screen. Penelope Cruz appears again in Sin fin (2018) on a poster showing the cover of a Vogue magazine at the Cadiz bus station, when Maria has given up acting while her partner in that videoclip, Penelope, has succeeded.