Visible crew/equipment: When Dewey yells for Lois because the bow was put on the present, if you look to the left of Lois, you will see a crewmember kneeling down, handing Lois the Red Dress, who is holding a bucket of water. He quickly gets out of the camera's view. [This is on the DVD of the first season. Someone said on the audio commentary that after catching it, they deliberately left it in to see if anyone would spot it. It's still a mistake, but that's why it's there.]
Visible crew/equipment: There is a man's elbow on the right of the screen near the start when only Jamie and Hal are in the room. (00:02:49)
Visible crew/equipment: When Hal is walking the stroller with Jamie inside at the park and Hal approaches the Body Builders, the full body of a camera-man and the camera he's filming with is ridiculously visible on the right side of the screen in a wide-shot.
Home Alone 4 - S1-E3
Visible crew/equipment: While Malcolm, Reese, Dewey, and Francis are deliberately making their house messy, you can see right above their ceiling a bright light shining down and a black background. It shows that they film their interior of their house on a set.
Visible crew/equipment: When Malcolm is first visiting Stevie, and Stevie is telling the joke, you can see the hair and hand of a crew member coaching Stevie through the joke.
Stupid Girl - S4-E4
Visible crew/equipment: When Hal is driving the steamroller at night alone in the car park - just before Dewey shows up - in the first shot there is a crewmen standing smiling in shorts to the side of the roller who then slowly walks out of view.
Visible crew/equipment: After the theme song ends it starts with Lois just finishing shaving Hal's back. Off to the side you can see the crew kneeling down.
Visible crew/equipment: When Hal rebuilds the track of dominoes, he walks out and slams the the door. This starts the dominoes falling. When it comes up to a shot of the American flag in dominoes, if you look closely to the left of the screen you can see a hand pushing it over.
Visible crew/equipment: In the scene where Stevie is in Malcolm's room. When Stevie is talking you can see the boom mike poking out at the bottom left part of the screen.
Visible crew/equipment: When Malcolm is talking to his first teacher, you can just about see a small part of a microphone at the top of the screen.
Long Drive - S4-E11
Visible crew/equipment: When Lois is yelling at the boys there is a camera visible on the left side of the frame. (00:01:40)
Visible crew/equipment: Towards the end, right after they watch the house blow up, you can see a hand holding a black object popping up from the right side of the screen. This happens right before Malcolm says, "Pretty sure".
Home Alone 4 - S1-E3
Visible crew/equipment: When the boys come out of the front door of the house to load into the van to go to the hospital the camera crew reflection is seen on the large picture window beside the front door.
Visible crew/equipment: When Lois gets in the car after she gets offended by the fact that everyone in the family forgot her birthday, you can see a cameraman with the camera reflected on the rear window when she leaves. (00:10:15)
Kitty's Back - S6-E5
Visible crew/equipment: A hand is visible on the left edge of the screen when Francis is talking to Dewey through the bathroom door. (00:15:50)
Visible crew/equipment: When Reese throws the sheet off the bed a hand can be seen in the bottom right corner. (00:12:40)
Reese Cooks - S2-E18
Visible crew/equipment: When Eric comes in to check on Francis, some crew members can be seen on the far left side of the screen. (00:13:45)
Dinner Out - S2-E4
Visible crew/equipment: Towards the end when Stevie punches Reese for the first time, his wheelchair swings back and a crew member holds and steadies it.
Answer: Francis is only allowed to talk on the phone at school for three minutes a day. I think the code gives him free access to talk to his girlfriend.