There must be hundreds of ways that Clark growing up on Earth could trip up Superman. Because Clark grew up here, Superman unconsciously knows something, does something or says something that a newly-arrived alien wouldn't. I was thinking about making this post and I realized that
Unusual Talents by Mouserocks is a good example (and a fun story).
I thought of two situations where information/terms were only used for a time and then outdated. I'm sure there are plenty of other types of trap.
For example, Superman walks up to a C64 and types L shift-I Return or does something comparable with an Apple II. The operating systems are completely different from the personal computers of 1995. Superman would have no way of knowing how an outdated computer operated, but Clark would.
Another example. For a very short time the medical scanner we know of as MRI was called NMR-Nuclear Magnetic Resonance imaging. "Nuclear"=Radiation in the mind of the radiologists unions so they objected to non-union operators running the equipment. As a result the name was changed to MRI-Magnetic Resonance Imaging. "NMR" was only around for ~6 months and anyone who even recognized the term in a medical situation would have had to been here. I remember the issue because I'm a geek but even though I know exactly what I'm looking for I can't find anything about the name change on the Internet. If an old-timer Emergency room physician asks Superman to take a patient to the NMR he shouldn't know to go to the MRI department.
What else? Points for obscurity and creativity. Megapoints if it comes with a story.
