Beezus and Ramona first appeared, as supporting characters, in a series of books focused on Henry Huggins. Beverly Cleary later wrote Beezus and Ramona, which actually focused on Beezus and her family. However, her younger sister Ramona became so popular, that the remaining books focused on Ramona. Beezus is still an important character, and Henry Huggins still appears, but became a secondary character in the series he launched. The names are reversed in the title for this film because of the shift in focus to Ramona.
The name of the construction company that builds the Quimby's new bedroom is called Bendix, a reference to the name of the doll that Ramona bakes into Beezus' birthday cake in the book "Beezus and Ramona".
Mr Quimby cuts the burrs out of Ramona's hair, creating several short layers on top. At Beezus and Hobart's wedding, which was planned in three days, Ramona's hair is back to all one long length. At the wedding Mr Quimby also mentions the phone call from Mrs Meacham was "a couple days ago," so enough time has not passed for Ramona's hair to grow back out.
When Ramona and Susan are talking in the music room, Ramona's top button goes from done to undone and back and forth a few more times. By the end of the conversation it has been undone for a few shots in a row, but when she gets up and goes to the window it is done again.
Just before Hobart proposes to Bea, he shows her a box full of old memorabilia that had been buried for years. The box is a Converse sneaker box of a newer sort with an attached lid. In the time frame the lost box was first buried, it would most likely have been different, with a detachable lid.
Bob Quimby: So, Beezus, suppose I told you that when I pulled up by the house tonight I saw your old buddy Henry staring at it like he left something important inside of it.