This film was shot in the subways stations of Buenos Aires.
In 2014, the San Jose station was painted with scenes from this movie.
The credited writer Armin Deutsch is the author of the much-anthologized short story "A Subway Named Mo(e)bius," first published in 1950 and set in Boston, Massachusetts, U.S.A. The subway referred to in the story is now part of the Massachusetts Bay Transportation Authority (the "T").