Chronograph wristwatch - Brad Pitt - Bullet Train
It might be a Breitling watch because Brad Pitt is a brand ambassador for Breitling since 2019.
Based on the spy shots from the film set (see images on the left) my first guess is that it's a Breitling Super AVI B04 Chronograph GMT 46 Tribute to Vought F4U Corsair, ref AB04451A1C1X1, with blue dial, steel case and black strap.
The steel case, shine of bezel, the dark dial (possibly subdials) and the shape of the buttons and crown lead me to believe that this is the Breitling Super AVI B04 Chronograph GMT 46.
If we get more images from the film we can maybe confirm this (last update: 14 January 2022).
Let's hope that Brad Pitt is indeed wearing this watch in the film, as this is a stunning watch. It sells for $10,100, see it at Breitling.
Bullet Train is an upcoming American action thriller film directed by David Leitch. The film is based on the novel Maria Beetle (published in the US as Bullet Train, see it on Amazon) by Kōtarō Isaka. The film stars an ensemble cast consisting of Brad Pitt, Joey King, Andrew Koji, Aaron Taylor-Johnson, Brian Tyree Henry, Zazie Beetz, Masi Oka, Michael Shannon, Logan Lerman, Hiroyuki Sanada, Karen Fukuhara, Bad Bunny and Sandra Bullock.
Brad Pitt also wears a watch in the 2022 movie The Lost City in which he makes a cameo appearance, but not enough images are available to ID that model.