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.
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.
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.
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: When Junior comes downstairs from shaving and enters the kitchen, his face and left ear have some smears of shaving cream. Junior walks into the den in the scene that immediately follows, and the smears of shaving cream have increased under his nose and on his left ear. (00:13:40)
Continuity mistake: In all of the episodes where Carmela hosts her film club, the theater seats in the Sopranos' screening room are gold, attached with wide trays for snacks, beverages, etc. But in this episode, when Tony and A.J. move the seats outside, they are maroon, without the wide trays.
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.
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.
Continuity mistake: Ralph's left ear is pierced. The prop of his cut head is not.
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.
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.
Continuity mistake: While Tony sits with his nephew, the peanut butter jar moves closer to the remote control between the first and second shot.
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.
Character mistake: During an argument between Tony and Carmela, they mention her ring, given to her in earlier episode. They refer to it as an emerald. It is a sapphire.
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.
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)
Answer: Yup, just like Nicholas Lea was chosen to play Alex Krycek on the X-files after showing up on 1 episode as a different character.
Grumpy Scot