Factual error: Company of Heroes is in the timeline of 1944-45. Soldiers are wearing the flag patch on their uniforms which have 50 stars on them, not 48. There were only 48 states in the U.S. back then.
Other mistake: Liesel goes to live with Papa and Mama in 1937, and starts attending school. About half way through the movie, 1942, Mama goes to school to tell her that Max was okay. Liesel is still sitting in the same chair and with the same teacher as in 1937, and the kids around her have not changed a bit.
Factual error: This film takes place in the north eastern USA. During the beautiful scene with the large black bird soaring above, they added a close up of an Andean Condor. The Andean Condor only lives in South America; Peru, Argentina, Chile, etc.