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.
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.
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.]
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.
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: You can see the crew right after the intro. (00:01:00)
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.
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.