While Coop is listing for Katie all the reasons he loves her, one of the things he says is "I love it that sometimes for no reason you're late for shul." "Shul" is a Yiddish term that refers (sometimes colloquially) to a Jewish house of worship (also known as a synagogue or a temple).
In late 2014, Netflix announced that they would shoot and air a miniseries continuation of this movie featuring nearly all of the same actors. However, instead of being a sequel, the new miniseries would be a prequel, with the actors (most of whom were already up to a decade too old to play their teenage characters back in 2001) playing even younger versions of the same characters they portrayed in the first movie.
Most of the cars and trucks (including the camp pick up truck) seen in this movie were built after 1981. With the exception of the camp van, and a few other vehicles.
The movie was largely based on the experiences the writers had at the camps they went to as kids: Camp Modin in Maine (David Wain) and Camp Mohawk in the Berkshires (Michael Showalter)