Visible crew/equipment: There is a camera operator visible in the reflection of Ethan's sunglasses in the funeral scene.
Visible crew/equipment: Just after Owen Davian is run over by the truck in Shanghai, Ethan chases the rabbit's foot down the street. There is a high angle street scene of Ethan running across the road. A cameraman is visible on the footpath following Ethan. Also, the traffic is going against the road markings. (01:26:35)
Visible crew/equipment: When Zhen arrives at the courtyard in the Vatican, a gentleman opens the car door. A cameraman and crew member are visible reflected in the door. (00:44:35)
Answer: It's never explained. This is what's known in the film industry as a McGuffin, a term popularised by Alfred Hitchcock, which is an item that's crucial to the plot, but the exact nature of which is never revealed because it actually doesn't matter in the slightest.
Tailkinker ★