The chase sequence in ‘The French Connection’ was filmed without obtaining permits from the city, featured many close calls with drivers and pedestrians who weren’t part of the film, and was shot by director William Friedkin himself because the other camera operators were married with children.

"Discussing the Brooklyn-filmed chase, Friedkin said he got permission to shoot on the elevated train after giving a New York official (who said the production was “crazy”) $40,000 and a one-way ticket to Jamaica."

[The Hollywood Reporter]