A bit off

I was enjoying Jonathan Franzen's piece in The New Yorker, "Growing up with Charlie Brown," when I came across this sentence:

The musical “You’re a Good Man, Charlie Brown” was in its second sold-out year on Broadway.

Franzen is referring to May 1970. Well, "You're A Good Man, Charlie Brown" was running off-Broadway. Furthermore, it opened in 1967, so it was in its third or fourth season by this point. It's first appearance on Broadway was in June 1971, where it lasted less than a month.

If this were a daily paper, I could see this slipping through, but what's happened to the vaunted fact-checking at The New Yorker?

Chicago Guy Adds: It's really gone downhill since Jay McInerney left.