The relationship between Elle and Vivienne is very underdeveloped in the musical, which is why it's sort of always a "What The Heck?" moment when Vivienne suddenly has her revelation. In the movie, you got to see Elle and Vivienne's friendship develop and we witnessed how the two graudally became closer.
Nothing like that happens in the musical. Vivienne hates Elle's guts right up until she does not. I wish we could have had a scene/song where Elle and Vivienne got to bond.
And everything everybody said about the Elle/Emmett relationship is true. She accomplishes almost nothing in the musical by herself, which makes the line in the finale all the more laughable. I HATED the fact that Emmett was placed in the trailer scene with Dewey and Paulette. What was significant about that scene in the movie was that Elle figured out the legal solution by herself. Heather Hach had Emmett standing there, giving her hints. It totally ruined it.
Sorry if I'm ranting, but I just hate how Legally Blonde's book was handled. Hach's book is most certainly the weakest element of the show.
"You drank a charm to kill John Proctor's wife! You drank a charm to kill Goody Proctor!" - Betty Parris to Abigail Williams in Arthur Miller's The Crucible