Kicked Out - S4-E12
Continuity mistake: Malcolm's seat belt changes from on to off the first scene with him and his mom in the car. When it's a shot from the front it's on, but when it's a shot from the side (from the driver's/mom side) you can see that the part of the seat belt that's going across is now behind Malcolm, instead of on him like it was a second ago. This changes back and forth.
Kicked Out - S4-E12
Plot hole: Malcolm mentions how his parents would flip if they knew he was still dating his lying girlfriend. But in the episode before (while in the car with Lois, at the end) he mentions how his girlfriend has him guessing what she wants to do. The way he says it, makes it known that he is still dating her. He says it in present tense. Therefore, they already know for sure, from his own mouth.
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.