Continuity mistake: The chain saw on the block of ice switches ice blocks more than once.
Continuity mistake: During the trial at the end, Jessup struggles with the MPs to get to Danny Kaffee. After the struggle, his tie is all out of place. In the following close-up shots, it's re-aligned, before becoming completely askew as Jessup goes to retrieve his hat.
Continuity mistake: When Sidney is fighting the killer, when ever a big stunt comes up, the killer's hair gets lighter.
Continuity mistake: There is no knife on the table when the wife enters the kitchen at the very end, however, she walks straight to Louis, hugs him and then magically a knife appears at the edge of the table which she picks up and uses to stab him (implied - the movie actually ends at that point).
Continuity mistake: In the scene with the lovely dancing ladies, Cotten blows cigar smoke just before a cut to him from the opposite angle. From this angle there is no smoke. This takes place just before Wells throws his jacket to Cotten.
Continuity mistake: In one of the first family scenes, the youngest daughter shows she has lost a tooth. The next shot, the tooth is back in her mouth. (00:15:10)
Continuity mistake: At the very end Fleming sees the dead body of his girlfriend being hoisted onto a gurney - she is soaking wet, having been hauled out of the swimming pool. Later we see it is a policewoman acting as a stand-in in order to fool him into talking - and after a few minutes under a blanket on the gurney she, her bikini, and her hair are all bone dry. Not only that, her hair looks like it has just been styled and her makeup is perfect.