Deliberate mistake: In this episode, Ray tells Amy's mother that Debra no longer reads his column, although she did when they were dating "and she was wooing me." But in an earlier episode, Ray proposed to Debra in his very first column - so when they were dating, he didn't have a column.
Continuity mistake: The large spoon and fork in Frank and Marie's kitchen change positions, right to left, and up and down. In some episodes the fork is on the right, and in others it is on the left. In other episodes, the fork is higher or lower than the spoon. At other times, the spoon and fork seem to be larger than at other times. It is obvious when she removes one of the utensils that they have never been moved - The Wallpaper underneath is a different shade from fading. If these were moved at subsequent times in the supposed feud, the difference in wallpaper fading would be seen.
Frank Barone: What's for brunch, Marie?
Marie Barone: Ham.
Frank Barone: Excellent. I shall put on my ham pants.