Continuity mistake: In the episode where Fiona is being harassed by Craig's wife, she's talking to Debbie about having a "birthday party." Debbie says her birthday is in October. Fast forward to season 7 when Monica returns and gets Franny back. She says she hasn't been that happy since the summer Debbie was born, to which Debbie replies that her birthday is in December.
Visible crew/equipment: When Monica stops the car, as Frank is getting out, you can see two cameramen in the reflection of the window. Also, a train is passing by but during the shot where Frank gets angry and makes a mean face at the camera, cars are passing along as if there is no train at all. (00:14:30)
Continuity mistake: After Fiona's return back home from the club where she's worked as a waitress, the blackish strips on her cheeks turn from partially rubbed off (justified by her wiping the tears) to perfectly fine a moment later, then change several more times during her discussion with Lip. (00:38:35 - 00:39:35)
Continuity mistake: When Monica and Frank are driving in the car with Liam, the Crawford Power Plant can be seen just behind the car. At this point, they have crossed the Stevenson Expressway and they are heading south down Pulaski. However, in the scene where they stop the car and argue, as Monica drives away, the Crawford Power Plant can be seen on the left, right ahead of them. (00:13:40 - 00:14:50)
Character mistake: Iain and Mickey tell paramedics about an old lady needing immediate help in her apartment on the "5th floor" just before stealing their ambulance as the paramedics storm into the building. However, the apartment building has lots of units on every floor and no unit # was given in this fairly large building. Medics would have trouble finding her had this been a real call.
Continuity mistake: A call comes through the police dispatch radio of a kid stealing from a liquor store and the address of the store is broadcasted as "44100 Western Ave", but when Carl and the lady cop enter the liquor store from the outside, the address above the store reads "2420."
Visible crew/equipment: Carl is walking along the reporters trying to get their attention. At the bottom of the screen is the shadow of the camera filming the shot. It moves as the scene moves. At one point there is even a boom mic shadow on the right. While this may be a member of the news crew, it's likely the boom mic for the show as the reporter has a mic of her own and the shadow follows Carl.
Continuity mistake: Apparently Debbie was born in October the beginning seasons. When Monica comes back and says something about the summer that Debbie was born, Debbie says she was born in December. In the earlier seasons (season 2 or 3), Fiona convinces Debbie to throw a party with kids her age, Debbie says her birthday isn't until October.