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.
Continuity mistake: When Christopher is trying to get rid of the body into the bin, his arms are constantly changing between crossed and hanging at his side. (00:30:30)
Continuity mistake: Tony gets out of the car near the start and there is no glass on the floor, when he calls Christopher over, broken glass on the ground has appeared.
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)
Continuity mistake: Christopher is trying to start a fire with sticks and has a cigarette in his mouth. He starts to go back into the van with the cigarette in his mouth but in the next shot the cigarette is gone and he is rubbing his hands together.
Continuity mistake: The table with the beer bottle by the pool gets closer to the chair after Tony sits down.
University - S3-E6
Continuity mistake: Tracey is cuddling Ralphie at home and places her hand on his belly. The left and right angles of her movement do not match: When she brings her hand towards herself, the following angle shows it on the opposite side.
University - S3-E6
Continuity mistake: When Ralphie and Tracey are at home, he places a dish with a cookie on his belly. The dish keeps moving up and down depending on the angle.
Other mistake: In the scene where Paulie Gualtieri goes to confront "Feech" La Manna at the bakery concerning the landscaping feud, the clock on the wall doesn't match the time on La Manna's watch or the clock on the wall behind La Manna's desk. The big clock says 11:55 while the other two say either 2:45 or 9:10.
Marco Polo - S5-E8
Continuity mistake: When Carmela is eating dinner with her parents and AJ, the amount of coke in her glass changes between front and rear shots.
Visible crew/equipment: During the dinner scene, in some of the shots facing Junior, the reflection of the boom operator (wearing a watch) holding up the boom pole/mic is visible on the glass, toward the top left side of the screen. Additionally, in two shots facing Junior (POV beside Carmela's right shoulder), we can see part of a black reflector screen (collapsible type) between Junior and Carmela.
Visible crew/equipment: When AJ tries on his new military school uniform, he's pressured to also put on the hat. Then, after AJ looks at himself in the mirror, just as he walks back toward his mother, the reflection of the boom mic becomes visible in that mirror directly over Carmela's reflection, at the right side of the screen.
Continuity mistake: When Janice goes to Livia's mailbox and retrieves the envelope with her disability check, the words "TOTAL DISABILITY" only appear on the check in the close-up, but not in the previous shot. Additionally, the silver screen door is gone between the first wide shot when Janice pulls the mail out of the mailbox, and the next close-up as Janice looks through the mail in her hands (she did not open the screen door between shots).
Guy Walks Into a Psychiatrist's Office - S2-E1
Visible crew/equipment: While Janice and Barbara are talking at the backyard barbecue, when Paulie appears, Janice makes a crack about him not being dead yet. It then cuts to Carmela and Janice walking down the home's outdoor steps, and the reflection of the moving boom mic is visible on the front door's glass, behind Carmela.
Visible crew/equipment: While Sal and AJ are at the batting cage, Matt starts telling AJ about the German philosopher Nietzsche. As the camera moves backwards in this dolly shot, we can see two metal T-marks on the ground, as well as the dolly track at the left side of the screen.
Moe n' Joe - S6-E10
Visible crew/equipment: After Vito drives by Satriale's, it cuts to the televised football game at the Soprano house, and when Meadow hands Bobby the beer, the reflection of overhead set lighting is visible on the side table's glass top.
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