Other mistake: When Fay is talking to Lowell over the walkie talkie, when she is giving him the recipe she is not pressing the button to talk, but Lowell still responds.
Return to Nantucket: Part 2 - S1-E4
Revealing mistake: Carol closes her eyes before Helen throws the pie in her face. There was no way she could have known it was coming because Helen was hiding the pie.
Joe: If ifs and buts were candy and nuts, we'd all have a wonderful Christmas.