I thought it was like a '68 Giulia but you're right looks like a 124 Sedan
Having nothing else to do tonight and since it's on Netflix I watched the whole movie. The car after the tunnel is definitely a Fiat and not an Alfa. If you want to check yourself it's at 1:38 or thereabouts.
I've always thought that "The Graduate" as far as Alfa Romeo fame is concerned was overblown. I never saw the movie until it was on late night reruns in the late 70's and we were way into Alfas before that and believe me it had nothing to do with Hollywood.