[onetimeuse92304]

They got the timing thing, but the flames totally unrealistic.

Flames are chemical reaction. Surface of the flame is where oxygen rich fresh air interfaces with fuel rich, oxygen-depleted hot plasma.

The nuclear bomb can cause secondary chemical fires, but the fireball itself has does not have "flame" look to it.

[thmsths]

Probably because they insisted on not using any CGI and doing everything with practical effects instead. I think this is an absolutist take and I would have preferred they used a bit of CGI were it's warranted. Like that nuclear detonation for instance. I couldn't explain why, but compared to the archive footage of nuclear explosion, it just felt wrong.