The new house that Annie and Izzy move into in California is the same house that was used in Another Cinderella Story (2008) with Selena Gomez.
The only film in the Legally Blonde franchise that both, went straight-to-video, and does not feature Reese Witherspoon as Elle Woods (though she does remain as producer). Elle's name is mentioned several times though, and the twins are her British cousins.
Becky and Milly Rosso, Brittany Curran, and Chad Broskey all appeared in The Suite Life of Zack and Cody (2005).
The signature move of the twins, Flip and Wave, is a recreation of the Bend and Snap routine by Elle Woods from the first Legally Blonde (2001).
As indicated by the title cards given to each girl in the beginning of the film, one way to tell each of the girls apart is that Izzie (Becky Rosso) wears hot pink clothes while Annie (Milly Rosso) wears soft pink clothes.
Feature film debut, and last film, of twin sisters and actresses Becky and Milly Rosso.