Filmed in the Hotel Marqués de Riscal.
On February 18th, 2022 (almost a year after filming finished) it was announced that the movie would be released on November 4th, 2022. That day, as an answer to an article on Twitter, director Álex de la Iglesia corrected that it wouldn't be a horror movie, and that the movie title would be 'BLA, BLA. CAR' (sic), instead of 'El cuarto pasajero' AKA 'El 4º pasajero', which was the title until that. On May 17th, 2022 it was announced that the release would be on October 28th, 2022, with the title 'BlaBlaCar'. However, on August 2nd, the poster was released, now with the title 'El cu4rto pasajero'.
Reunites Alberto San Juan with Blanca Suárez after El Test (2022), where they played a couple in love troubles.
Alberto San Juan and Blanca Suárez are indeed separate 20 years from each other.
In the movie Lorena, Rodrigo and Sergio contact with Julián for traveling from Bilbao to Madrid. Bilbao is a city belonging the province of Vizcaya and the autonomous community of Basque Country (north to Spain), while Madrid is a city belonging the autonomous community of the same name (center to Spain; as autonomous community, Madrid has no provinces). The two cities are distant each other about 248 miles (400 km). Not counting possible traffic jams, a car ride from one place to another lasts about 4-5 hours.