The movie has Stratton's debut against the New York Yankees. Monty Stratton actually debuted against the Detroit Tigers (June 2, 1934).
Post amputation, Stewart fails to maintain stiff leg and foot when batting. There is a shot where he flexes his toes and several where the bending of his knee can be seen. (Could have been easily remedied with a brace [to include the foot]).
In Monte Stratton's pitching debut versus the NY Yankees, Joe DiMaggio is shown circling the bases in stock footage. However, Stratton debuted in 1934 and DiMaggio didn't show up in the majors until 1936.
Stratton broke into the majors in 1934. But the movie depicts the White Sox wearing their 1936 home uniforms.
Through the entire movie Ethel wears the same hairdo, a late 1940s fashion that obviously did not exist in the 1930s.
At the end of Monty and Barney's hitchhiking montage, they are shown standing by a sign that says "Pasadena 27, Los Angeles 35." It's about an 11-mile distance between downtown Pasadena and Los Angeles - that means there's no place on Earth they could stand and have that signpost be accurate. Those closest spot would be northeast of Los Angeles on the other side of the San Gabriel Mountains, which in itself is an improbable spot to be since they were coming from Texas.