Ma sent a freshly baked and frosted birthday cake to her son Doc Barker all the way from Ocklawaha, Florida to Chicago, Illinois. When it arrived the cake arrived in Chicago there are birthday candles on top of it that weren't there when it was placed in the box.
When the final motel Ma and her four boys are staying at is first shown, a sign in the window advertises that the rooms have TV, over a decade before commercial TV was available in Minnesota.
The $10 bill that Doc spends out of the ransom money is from the postwar era, as the Federal Reserve bank symbol is much smaller than those from the 1930s.