The title is a parody of the TV show title, "Murder She Wrote" which is about an old lady who solves crimes.

The test Mr. DeMartino hands back seems to be nothing more than five multiple choice questions... how can you get a 66% on that?

We've seen hints that Kevin's been involved in theft before. In "Cafe Disaffecto" when Kevin is asked how he feels about the theft he gets very defensive and denies he did it.

Jane's comment about grading herself on a curve is a reference to a standard US school practice that involves making the average of the class's score a C rather than simply grading everyone on a percentage of correctly answered questions.
Note: The "grade on a curve" title is also applied to other, slightly different styles of grading, but I think the above is most common.

When Jake goes detective, he's based on Inspector Clouseau of the movie "The Pink Panther"

The Fashion Club turn into a self-parody of the old TV show "Charlie's Angels"

"Et tu, Mack Daddy" is a reference to Shakespeare's play "Julius Caesar"

Well-endowed women tend to have problems using bows... Brittany shouldn't have been able to hit much of anything except herself.