It is probably not hard for you to guess that I am a fan of the television show Mad Men. I first began watching it for the props and costumes, but the dialogue, acting and slow-to-build plotlines are quite good, too. I'm always on the lookout for the typewriters shown in the office or other scenes. There is an anachronism with the model of IBM Selectric typewriters, though. The models shown did not come out until 1961, a year after the timeline set in the show. It is apparently explained in passing— the Sterling Cooper advertising agency handles the Selectric account. (You can occasionally catch a glimpse of an authentic typewriter ad hanging on an office wall.)
The AMC Mad Men website is full of great supplemental content such as behind-the-scenes, photos and interviews (I've spent a lot of time there today!), especially their 1960s Handbook that gives some historical context. This article (and link) about early photocopiers is quite interesting.
IBM typewriter photo from Flickr.