Awesome Music: Regardless of the few temporal goofs with the music, the choice of tracks is splendid and fits very well. Whether you were around the 1960s or just love them, the songs that play really set the moods for each scene. Janis Joplin's "Summertime" makes you feel like you're right there in the Catskills trying to beat the heat, and Jefferson Airplane's "Today" playing while the moon is landing as Pearl gives in to Walker is incredibly evocative.
Starting the movie with Bobby Darin's "More" and ending with "Purple Haze" also doubles as Ironic Echo.
Double Standard: With a dose of Protagonist-Centered Morality as well. Had this been the other way around with Marty cheating on Pearl with an attractive woman (bonus points if she's a Shiksa Goddess) just because neither of them got to live it up when they were young, the viewers would judge him more harshly. Marty's a dutiful father and husband, very attractive, and their marriage is not sexless but we're supposed to cheer for Pearl schtupping the blouse man to make up for lost time!
Jerkass Woobie: It is very easy to feel angry and sorry for Marty at first. But then he goes from Woobie to Jerkass right after finding out about the affair by displacing his anger at Pearl onto their kids and other people; such as nearly breaking TV sets he has to work on and he kisses another man's wife in retaliation. Marty then tries to take Daniel and Alison away in the middle of the night.
Marty: Gee, maybe you should screw the dress man instead, at least this way you'd have an entire outfit.
Then he reclaims his Woobie status back in Brooklyn, sadly rummaging through his children's belongings.