Revealing mistake: In the scene where Reese Witherspoon is entering the elevator after being harassed by her mentor, you can see Selma Blair's reflection in the plaque right before her cue. You see her reflection right before the doors close, so you know she was waiting for the cue.
Audio problem: In the scene after Reese Witherspoon and Luke Wilson are returning from questioning the ex-wife of the murder victim at a spa, they are driving up in Luke's car. You can clearly see, as they get closer to the camera, that what you hear Luke saying isn't what his lips are saying. It was a very obvious dub over...and a very bad one.
Revealing mistake: When Elle is talking to Paulette on the cell phone, while waiting for the water, the woman before her goes to the water fountain, and you see her. She doesn't drink any water. She just puts her mouth next to the fountain. It is extremely obvious.
Continuity mistake: When Elle decides to quit law school and goes to see Paulette at the nail salon, when she arrives she's crying and her face is wet with tears. In the next camera angle (2 seconds later) her face is completely dry and her makeup is normal.
Continuity mistake: In one of the courtroom scenes, you can see Paulette (the nail technician) enter with the UPS guy who has plaster on his nose - the plaster is white and has two brown pieces of tape over it. At the end of the same scene when everyone is exiting the courtroom, the UPS guy has no plaster only two, now white, pieces of tape on his nose.
Continuity mistake: When Elle is called to the lawyer (Callahan), she holds some files and no bag. After he tries to pick her up, she leaves with empty hands. A few seconds later, in the corridor, she's walking with her bag on her shoulder. Where could she get it from? And did she have the time to put the files in?
Continuity mistake: When Elle's boyfriend picks her up to go to the restaurant his hair has a parting. In the restaurant it is slicked back, after, in the car the parting is on the other side
Continuity mistake: When Elle is walking out after she won her case her hair is a very light blonde and wavy around the face. In the next scene when Warner is begging Elle to come back, her hair is much darker and it's curled under at the ends of her hair.
Continuity mistake: Near the end of the movie, when Elle walks out with Brooke, she is holding Bruiser in her left folded arm, with her dog-carrier purse, that looks like it has something in it, on her right shoulder. A few seconds later, when Warner approaches her on the steps, she has no dog but the purse looks empty.
Continuity mistake: After Elle gets dumped by her boyfriend (near the beginning), she is walking along the street and shots switch between her and her (ex)boyfriend in the car. The shot switches to her and suddenly her hair is quite messed up.
Other mistake: Legally Blonde was shot at a Delta Zeta Sorority house (a Z is very easy to change into an N). Proof of this can be seen in the scene at the beginning of the movie when there is a shot of the entranceway floor. On the emblem of the floor there is a Greek delta and what at first glance appears to be a N. However, if you look at the delta at the proper angle the N is a Z.
Continuity mistake: When Elle is at the beauty salon she has 2 flowers in her hair, one purple, and one pink. When the camera angle changes, the flowers also change position from shot to shot.
Revealing mistake: When Elle and Emmett are talking on the benches, a girl in a blue-gray shirt and red tie leaves the building twice.
Continuity mistake: When Reese Witherspoon is eating chocolates after being dumped, look closely at the box. When she finds one that she likes, there are two white ones one row in from the back. Two seconds later, just before she throws the box at the screen, there's only one white one, and it's moved forwards a row.
Visible crew/equipment: After Elle gets in the elevator, right after the door shuts, look for a crew guy crouching down next to her in the door's reflection. He is only visible in the Standard screen option, not Widescreen.
Continuity mistake: In the scene where Elle saw Warner at Harvard she talks to him and starts walking down the hallway. Her purse is on her left shoulder. The camera goes back to showing Warner and then back to Elle. Her purse is then on her right shoulder.
Continuity mistake: In the scene where Elle is at the beauty salon for the first time, she had parked right in front of the salon behind a brown car, but when she goes inside you can't see her car outside, just the brown car.
Continuity mistake: When Margo is picking out her wedding dress, Serena has short hair, but in the courtroom scene, she has long hair.
Continuity mistake: When Elle is visiting Brooke in jail and takes her all of the goodies in the basket. Elle holds up the "Bible", (cosmopolitan magazine) and Elle's hair is behind her ear, yet in all of the other shots of Elle on the phone, her hair is down and the phone is on her hair.