One of the wrecked tanks on the train, near the beginning, was a British Matilda, of which about 1,000 were supplied to Russia.
In the scenes where the "White Tiger" tank appears, it often emerges from blankets of thick fog, to give it a supernatural presence. It often disappears into the same thick fog, to make it seem invincible
The White Tiger tank is neither a Tiger nor a Tiger P. It's a Russian IS-2 modified to look like a Tiger tank--that's why the turret is moved to the front of the tank. Tigers also didn't have the tracks covered; this is most likely done here to hide the fact the wheels on the Tiger and the IS-2 look very different. It's believed that the American film Fury (2014) was the first to use a real Tiger tank.
When the White Tiger is first seen, it clearly has the turret mounted toward the front of the vehicle, instead of the middle as in the iconic Tiger design. This identifies it as a Porsche prototype, which lost to the more reliable Henschel design in early trials. As such, only one Porsche Tiger ever saw combat service. It served as a command tank on the Eastern Front in 1944, and had additional front armor of up to 200mm thick. Just like the tank in the film, this would have made it virtually immune to most Soviet tank and anti-tank guns.
Although Fury is believed to have been first to feature a Tiger tank, it wasn't. A French film, La Neige et le Feu (1991), set in the closing stages of the Liberation of France featured a Tiger from the Saumur tank museum, the only functional Tiger at the time.