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.
Factual error: Robert begins as a SGT in the NYPD (later promoted to LT). However, he has issued speeding tickets in his brother's/parent's neighborhood. The family Barone lives in Lynbrook NY. Lynbrook is part of Nassau County, Long Island, which is not part of NYC. Robert would have no jurisdiction to issue speeding tickets there.
Factual error: Robert, as a police officer in NY State, is bound by law to carry his weapon at all times. Robert is never seen with a firearm, not even when in uniform. A police officer would not have his sole sidearm strapped to his calf or ankle under his pant leg, making it hard to access in a situation where he would need to be able to draw it at a moment's notice.