On this website I have a list of all the times I know about Iowa mentions or settings in various forms of entertainment, but it looks like I’ve been one-upped. Way upped. The Des Moines Register reprints a much, much larger compilation of Iowa references in movies, by two people who will be putting it into a book. The blurbs are short and clipped, much like I use for the list. If the link doesn’t die, that will be a much better source for film, although my list will still be here in a different style of sorting.
I’ve added the link to the references page.