That scuffmark on the door has always bugged me. It's just that the episode's director makes such an absolutely clear point of that scuffmark on the door as it's actually being made. The camera really focuses on it right there and then. To me it seems that the viewer shouldn't be being told so "up front" about that scuffmark. It's the sort of thing that we should have been told about later in the episode. Then, on repeat viewing, we would look out for it and when it happens, we would say, "Oh yeah, he does scuff up the door when he carries the body through!" The exact same thing holds true of the murderer smoking the cigar in the murderee's living room!

Of course, at the time it was made, the director/producers probably didn't think that viewers would be viewing it hundreds more times each!