I was flying once on a company-issued ticket that had me down as Captain Chuks when someone spotted that ... and asked me if I was perhaps in the Army.
Great for the ego, being taken for a guy in his mid-fifties who has never got beyond O-3! I just laughed and said that, no, I was a professional pilot on a company ticket, that was all.
In my opinion it's one thing to don a costume and act in a movie. It's understood then that John Travolta never killed anyone, even though we've seen him do that. To be there in a real aircraft; wearing a real Captain's uniform; being taken by many for being "fully qualified" even though you can read "B707 SIC PRIVILEGES ONLY" right there on the FAA page ... that is taking dressing up and playing Captain a bit too far.
I have had people tell me in great detail about how Travolta has an ATPL and a CFI and an FE, and, and, and ... when I suspect that Travolta's publicist is happy to see that happen. Travolta himself has never bothered to correct any mistakes about his qualifications, and that suggests that he's happy to use aviation for publicity purposes.
I remember once catching a bit of an Oprah broadcast where she told her select audience that they were all to be flown to Oz in an A380 piloted by John Travolta himself, so what about that? There was no need for that "APPLAUSE" sign that time, I can tell you. Travolta must have been on the jump seat saying "Oz is that way, Boys, so give her the berries!" Piloting ... without ever touching the controls, one assumes.