Of course it was a Porsche Design by Orfina with 5100. That was one of the mechanical chronographs you could find in the 80s and the one of the 5100 regularly issued to NATO pilots along to Tutimas, Heuers, Lemanias, Arctos etc...etc...
That particular watch was lent by a real pilot because Cruise was wearing something gaudy and completely unappropriate for a military pilot. Brigitte Nielsen also wore a PD Orfina in Beverly Hills Cop II, and it appeared in one of Chuck Norris films.
American pilots were not issued these watches like European ones but they were popular as private purchase, this is the way a NATO issued 1717 looks like:
Cruise and its legitimate owner however had a civil reference 1716 like mine.
Oh, in the 80s it costed three times a manual Daytona and the Lemania 5100 was selected by NATO in 1978 against the Valjoux 7750 because it could withstand 7g without losing time, therefore we can say it was the last real mechanical military watch ever issued for its use along with the Poljot 31659 of the same era.