Corrected entry: When the guys first get to the track, Hal says they have 4 hours of this. When Caroline gets to Malcolm's house she said Malcolm had been ditching school. But then, when the story goes back to the guys, they are still at the track. I wouldn't think that Caroline would leave the school to come and talk to Lois. And I also don't think Malcolm only has 4 hours of school.
Corrected entry: In this episode, Lois tape records the boys singing and dancing and says she'll show the tape to their friends at their next birthday (key word 'next'). But in "Forwards Backwards" we find out that Malcolm and Reese have never had a birthday party in their entire lives.