Hamilton Khaki Field - James Marsden - Sonic The Hedgehog 2
The watch worn by James Marsden has a black dial, stainless steel case and green NATO strap, so most likely the Khaki Field Mechanical H69529933 (42mm, but it could also be the smaller 38mm version). The strap is the green NATO strap with brown leather bands as can be seen i the close-up photo.
See all Khaki Field models on Hamilton.com.
The Hamilton Khaki Field is a classic field watch and seen in several films (see a list here).
In Sonic 2, two other characters in the film wear Hamilton watches as well: the Hamilton Khaki Navy BeLOWZERO worn by Tom Butler and Hamilton Intra-Matic Auto Chrono worn by Shemar Moore.
In the Sonic The Hedgehog movies, James Marsden plays Thomas "Tom" Michael Wachowski, the sheriff of Green Hills, known to Sonic as "Donut Lord".