How do you tell where a film has been filmed?

I look for these three:

- Plates of cars in the background

- Outlets

- Other wiring details

Hollywood tend to place American outlets in any place of the world... Swedish films of course feature Swedish outlets anywhere. [Linked Image] To the film makers credit: They do take care not to put new switches and outlets in "old" films.

BTW: Do those weird American paper bags without handles you see in films exist in reality?