For All Debts Public and Private - S4-E1
Continuity mistake: Tony is clean-shaven at the doctor's office with Uncle Junior in the lobby and when he makes eyes with the nurse in the hall. However, steps away in the exam room, Tony now has a five o'clock shadow. (00:11:11 - 00:11:32)
For All Debts Public and Private - S4-E1
Continuity mistake: Tony throws the newspaper at his son and it lands with a corner folded on the cereal bowl. From the opposite angle it is laying straight on the table.
For All Debts Public and Private - S4-E1
Continuity mistake: When Chris places the twenty dollar bill on the fridge, there's a picture of a fat kid next to it. Depending on the angle, a paper covers/not part of the photo.
For All Debts Public and Private - S4-E1
Continuity mistake: When Tony Jr. reads the newspaper, his part of the table changes completely: The napkin changes position, the orange juice comes closer to his arm, the spoon in the bowl changes positions, and a mug in front is replaced for a load of papers. The position of his thumb also swaps from being beneath a photo, to on top of it depending on the angle.
Continuity mistake: During FBI questioning, Adriana vomits on the conference table. Bureau Chief Cubitoso is sitting to her left, and in the scene, he has no vomit on his clothes or face. However, in the next close-up shot, he has vomit on his shirt and face. (00:51:23)
Continuity mistake: During FBI questioning, Adriana vomits on the conference table. Agent Deborah Ciccerone is sitting directly in front of her, and in the scene she gets no vomit on her clothes or body. But in the next close-up shot, she has very long vomit on her blouse and jacket, despite sitting across from Adriana. (00:51:23)
Revealing mistake: When Patsy knocks down the black guy with the iron pole, the pole breaks in half like a piece of plastic. When it cuts, the pole is intact.
Christopher - S4-E3
Continuity mistake: When Gabriella confronts Father Phil about the public speaker, the cannoli that Father Phil has in front of him changes halfway through the scene.
Revealing mistake: A different horse is used for close-ups and race shots; you can tell by looking at the white patch on Pie-O-My's head, which is much bigger in the close-ups.
Continuity mistake: While standing outside the horse's stall, Ralphie's arms go from being at his sides, to folded across his chest throughout the whole scene.
Continuity mistake: When Tony speaks to Artie at his home, Artie is seen putting a cigarette in his mouth. However, in the next shot the cigarette has disappeared and Artie is drinking from his cup instead. (00:18:35)
Watching Too Much Television - S4-E7
Visible crew/equipment: When Furio is at the Sopranos' to pick up Tony and tells Carmela he'll be waiting in the car, a crew member can be seen reflected in the door glass as Carmela closes the door. (00:38:55)
Continuity mistake: Ralph's left ear is pierced. The prop of his cut head is not.
Continuity mistake: While Tony sits with his nephew, the peanut butter jar moves closer to the remote control between the first and second shot.
The Strong, Silent Type - S4-E10
Continuity mistake: Tony gives Corrado a glass of wine, holding it from the sides. A frame later his hand is on top of the glass.
The Strong, Silent Type - S4-E10
Revealing mistake: Christopher is high from shooting heroin and sits on Adriana's dog and kills it. She comes home and calls for the dog and sees her under Christopher. He picks her up and you can plainly tell its a stuffed dog.
Answer: It's a mafia thing. Taking food off another made man's plate in public view like that is comparable to the guy in Casino taking off his boots and putting his smelly feet up on the table.
It is not a "mafia" thing, it's basic manners and plain gross for another person to stick their fingers into a plate of your own food. Same with the feet on the gaming table scene in Casino. It's not a "mafia" thing, it's just rude and not something a person does in public.