Right after when Ozzy returns to the Uvula via one of Shane's tears and Leah, Cheif, and Driz are standing around him waiting for him to wake up, Drix's mouth can be seen moving even though he is clearly not saying anything.
When Shane decides not to go to Buffalo with Frank, we see the ticker above his door showing the scores of various sports games. The item "Seattle: 5 Oakland: 4" scrolls onto the screen in two consecutive shots.
Chill was sent into Frank as a flu vaccine. While he could have been a live, weakened virus had he been administered via LAIV (FluMist), this variety of the vaccine was not introduced until 2 years after the film was released. So Chill would have had to come from an injection, meaning he would be a dead virus.
In the scene where Frank converses with the oyster boy, the latter says something about 'the oysters should be edible...if my hypothenuse is correct'. The correct line is 'if my HYPOTHESIS is correct.'
The false eyelash that Shane is wearing changes positions between scenes. When it's first put on her eye on the bus, the falsie is above her eye. However, in the hospital, the falsie has moved to the bottom of her eye. (The position of the falsie is rather obvious in close up shots when Ozzy and Thrax are fighting on it.)