It's may be a fake, but it is possible it was used as a movie prop. It's actually pretty common for fakes/replicas/etc. to be used as props for TV or movies. You see this when celebrities auction stuff they used in movies, you often see fakes in the offerings.
There's a somewhat popular GQ video of Robert Downey, Jr., showing off his watch collection (some of which he got working on movies). One of his watches is actually a fake Speedmaster
(See 0:54 mark)
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