Edward Norton wears a Polar F5

I can think of maybe one movie watch the plot actually needs, and it is on Bruce Banner's wrist. In The Incredible Hulk, Louis Leterrier's 2008 film, Edward Norton's Banner is holed up in a Rio de Janeiro favela, working a bottling-plant line and running breathing drills to keep his pulse down, because if his heart rate climbs too high the Hulk comes out. The thing on his wrist is not jewelry, it is an alarm. Liv Tyler plays Betty Ross; Tim Roth is Emil Blonsky, the special-ops soldier hunting him who later becomes the Abomination; William Hurt is General Thaddeus "Thunderbolt" Ross, running the manhunt.

The watch is a Polar F5, a Finnish heart-rate monitor sold to gym-goers in the mid-2000s, and there is something right about that casting. Polar was founded in 1977 and built the first wireless wearable heart-rate monitor in 1982, the Sport Tester PE 2000, so a man whose life depends on reading his own pulse is wearing a device from the company that more or less invented the category. Screen-used examples from the Brazil scenes still turn up in the prop market, including a working hero watch and a "broken" one that matches the shot where the Hulk's growth rips it off his wrist.

And then they filmed it wrong. A real Polar F5 takes its reading from a wireless chest strap, continuously, with no pulse pad anywhere on the watch face. Banner keeps pressing a finger to the watch to check his heart rate, which is the one thing an F5 cannot do, and IMDb files it under goofs. They picked the exact right watch for the story - a pulse alarm for a man who cannot let his pulse spike - and then had him work it in the one way the hardware never could. Norton played Banner only this once before the role went to Mark Ruffalo, so this fussy little heart monitor only ever got its one film.