I saw this movie on PBS in New York many years ago and unfortunately before video tape. I recall reading an article about the way some of the special effects were done. Remember Cohan is playing two roles. There are many scenes in which he is talking and acting with himself. There is a particularly interesting scene on the front porch of an old house. Cohan #1 is in a rocking chair when Cohan #2 approaches him; Cohan #1 gets up to shake hands with Cohan #2- thereby shaking hands with himself. The rocking chair in the background continues to rock. After the hand shake they reverse positions and Cohan #2 walks up and gets into the rocking chair, which has never stopped rocking. Cohan #1 looks on. Done done in split screen? Apparently. but the effects artist died shortly after the film was made and to this day no one knows how he produced the effect. Great line by Colbert's character: "The night's so lovely you could eat it with a spoon".