I did a similar thread about “I swear to you” being an oath. Does saying “I could’ve sworn…” count as an oath or does using that when lying count as a serious sin? How about for actors? I don’t have a habit of saying phrases like that but I’m interested in knowing.
Saying “I could’ve sworn …” is not an oath and saying these words is not a sin. I can’t comment on the lie that might go with it.
The same goes for actors. In any case, if they’re speaking the words in the context of a performance, whatever an actor says, they’re not making an oath and it’s not a sin.