A couple more slip-ups from Columbo's series debut that I haven't seen on the Goofs page...
During the final confrontation scene, look closely at Columbo's coat. It goes back and forth between being completely unbuttoned and having the bottom button fastened.
Also, when Ken walks out of the cabin to his car after killing Jim, you can see what appears to be the shadow of someone's head appear on the right side of the screen. Could this be Steven Spielberg's Hitchcock-like cameo? Or just a mistake?
Yeah, there are lots of goofs/errors/holes in this one, but the cast makes up for it. It just seems odd given that its director is supposed to be some sort of deity.