NY Times Article on the filming of 'The Odd Couple'
I found a great news article date July 2, 1967 where the newspaper writer and photographer were on location of the movie, during the rooftop scene. I'd always wondered what building that scene was filmed at, and it's 190 Riverside Dr.
The article also included interviews with Matthau, Lemmon and director Gene Saks. Lemmon breifly discussed the New York scenes that were shot earlier in the week at Metropole (Go-Go Club), and the Flanders hotel (during credit sequence). Lemmon also said he had even stayed at that same hotel as a struggling actor.
Lemmon mentions a scene where he falls into a lake, and another where he spends time at another bar called Martha's. Apparantly those scenes ended up on the cutting room floor.
Much is made of the muggy 80 degree nights. So those night scenes around New York were pretty authenic!