In the opening, there is a reference made to Elle Woods crying at the age of 3 whenever she was taken to BabyGap. BabyGap didn't exist until 1990, when the character was probably about 9 or 10. Even GapKids didn't open until 1986, well after the character would have been 3.
In the hearing for Bruiser's Bill, Elle puts Bruiser in his bag on the table beside her. You can hear her say "my best friend" but as there's a cut to a close-up of Bruiser, you can see Elle's lips in the right hand corner, forming the words "my best friend" silently.
The first time Elle introduces the Snap Cup, she is holding the cup in her right hand and paper in her left. When it comes time to snap she makes a snapping motion with her left hand while still holding the paper and a snapping sound is heard. There is no way her fingers could actually make the snapping sound with the paper in the way.
When Congresswoman Rudd is standing outside her office to tell Elle that C'es Manifique was going to release all test animals, her necklace is inside her jacket. As she walks into her office, the necklace is outside the jacket and hanging askew. When she turns around to talk to Elle again, the necklace is once again inside her jacket.
When Elle comes out of the elevator at her job, the flower on top of her hat is facing forward above her right ear. But in the shot of her walking down the hall delivering coffee, the flower is now on the back of the hat and behind her right ear.
When Elle calls to activate the Delta Nu phone tree, there is screaming at the Delta Nu house and then they hang up the phone. Then Elle is shown on the phone still listening to screaming until she hangs up.
You see a crowd of people on the Capitol steps as Elle enters the Capitol Building. In fact, all of the buildings on Capitol Hill are connected by halls underground and people who visit and work at the capital almost never go from one building to another above ground.
In the scrapbook of the opening sequence, there is a page with "First day at Harvard" spelled out in Scrabble pieces. The value of the tiles are not correct Scrabble values, as A has a value of 2 (should be 1), V has a value of 12 (instead of 4), R is 7 (instead of 1), etc.
In the last scene when Emmet asks Elle where she would like to live.In the next shot when the White House is shown and then the shot comes back to Elle, Emmet can no longer be seen beside her, as it clear it's a computer generated shot of Elle.