A few years ago I watched a movie -- can't even remember what it was -- that heavily involved pagers. One character got mad at another for not returning their call, and there was a dramatic scene where they yelled something like "I PAGED you like an HOUR ago!" At the time of its release it probably made perfect sense, but from a modern perspective it had some unintentional comedy to it -- not to mention that younger audiences might not even understand what was going on given that pagers have likely fallen out of common understanding at this point.
I'm curious as to other things that haven't aged well, whether that's due to technological changes, shifts of the social or moral landscape, or even things that are fine in isolation but are hard to divorce from a larger context (e.g. They Might Be Giants released a song in late 2011 that jokes about Whitney Houston being the drummer for the band, but Houston died unexpectedly in early 2012).
Really anything is fair game: what hasn't aged well, and why not?