I am not sure how far Photoshop takes their filters but those bills aren't actually replicas nor can they be mistaken on reasonable examination (a cashier glancing at them)

Typically their texts read "For movie use only" over the seals in the middle or other things that make it clearly distinguishable as fake money that isn't legal tender. I think some of them flip the heads backwards or do other things so it immediately fails the sniff test.

Adam Savage actually has multiple videos on how it is made, super fascinating stuff! https://www.youtube.com/watch?v=drLzVcgnBfI

(Thank you for asking this, I was dying to gush about how cool movie money is)

In some movies those are actual real money. Just the top layer.

Dealing with legislation, lawyers and legal compliance is soo expensive, they would rather use a few thousand real dollars for couple of hours.