At the mental hospital where Sophie has been admitted, Susie is given a list of Sophie's paramours whom Susie is not to mention. The second name is incorrectly given as "EDGAR G. Robinson" and not "EDWARD G. Robinson".
When Midge first goes back stage at the strip club, she stands by some vertical lighting poles with stage lights on them. The particular model of stage light shown, the Altman 360Q ellipsoidal spotlight, was not introduced until 1974. Tiny detail, but theatre folk know.