I won't rehash what the other reviewers have said, other than to say that most were a bit too generous. Even though this B-movie had a running time of only 67 minutes, it seemed to me more like 3 hours, as the whole story was so tedious. Everything about it is flat and stale - the production values, the acting, the writing, and especially the "humor". I am guessing it seemed old hat even in 1941. I gave it a watch because Marian Marsh was in it, and she was incredibly captivating in several of her films of the 1930's. Here she is mostly wasted. There is one basic principle shortchanged here, and it is one that I believe is basic to any kind of drama (comedy or serious, from wild fantasy to kitchen-sink realism) - the sense that those involved in the production - from the writer to the director to the actors - are playing for keeps, giving it their best. That doesn't happen here - everyone seems to be "phoning it in".
Review of Murder by Invitation
