Goofs

Francesca says that Harry still thinks of himself as a private; while Harry has confessed that he was "recently promoted", he never told her that he was originally a private.

The British Army and Royal Marines eliminated the rank of Brigadier General in 1921. In 1943, as today, the British Army has the rank of Brigadier.

A Brigadier is above a colonel and below a Major General, but British regulations do not consider it a General rank. Rather it's Field Grade, like high colonel.

After NATO was formed, a table standardization made the Brigadier equal to Brigadier General to eliminate confusion.

In 1943, out of Courtesy, American and French officers would treat them as One-Star rank, but in terms of determining command seniority, they would be junior to their American and French counterparts.

If nothing else, the British would never refer to themselves as Brigadier Generals.

The signage, both the title on the office door in London and the Dymo tape labels on the generator switches in the German POW camp are of a type that did not come into use until after the war.

The Countess's clothing and hairstyles are more of the 1960s than the 1940s.

Generals Armstrong and Pennypacker wear service branch insignia on the collars of their Class A uniforms. General officers in the US Army, then as now, do not wear such insignia. "General" Frigg's uniform is a correct representation of officers of that high rank.