Factual error: The truck's gas tank is said to be empty, but is able to explode spectacularly later on. An empty gas tank may spout a jet of flame, but will not have enough force to rupture and damage the truck, a full tank of liquid gas will not burn unless vaporized. Simply put the truck would not explode in that Michael Bay fashion.
Factual error: During the opening credits, Jack Lemmon walks past two "sailors" in dress whites. If they were actual sailors, they would have rate insignia on the left sleeve, service ribbons on the left breast, and a rocker patch on the right shoulder seam.
Factual error: The revolvers carried and used by Sir Sidney Ruff-Diamond, Captain Keene and Sergeant Major Mcnutt throughout the film (and particularly at the end fight) are Webley MkVI's, not introduced into the British Army until 1915, 20 years after the film is set. Additionally, the holsters Keene and Mcnutt carry them in are webbing holsters, not introduced until well after WW1 (1914-1918).