I would like one of those Star Trek time travel episodes where they go to the present (2016). But instead of choosing attire that allows them to blend in, they get their research wrong and we all see that immediately.
For example, a TNG episode. Data declares that through extensive research, he’s sure that they will now be incognito in 2016. They step out onto the street and that’s when we realize that Data has mistakenly labeled Game of Thrones as non fiction and they are all dressed in huge furs, capes and have swords.
Data: I seem to have made an error, Commander.
Riker: I agree.
Worf: I like it.
Or, which is an idea I might love even more: They don’t realize it. They just walk around and everything about them is SUPER WRONG.
This is how I imagine we would spot aliens. Those green bastards knows nothing about fashion.
People would likely just assume it was a LARP outing, or maybe a play or a movie was being shot nearby. That’s probably the best cover any aliens or time travellers could use; just pose as actors and a film crew with really well made props, and did you know we’re able to shoot CG effects live now?