How do you deal with 'throw away characters' (characters only in one scene)?

Sometimes it's necessary to have scenes with characters who only show up once. They're in for long enough that not having a noun or pronoun for them seems clunky.

But at the same time, I don't want the reader to think these characters need to be remembered after this scene.

I can sometimes get away with calling them 'the teacher' or 'the police officer' but I do have scenes this won't work.

Would you just give them names? Find an identifiable feature etc?

Especially compounded by the fact the MC in the scene would know their names.

Any help is welcome!