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".
Klickitat St. is a real street in North East Portland, OR, where author Beverly Cleary grew up. When we see Ramona waiting for the bus and the number 73 rolls up, that would have been near the corner of Klickitat St. and 33rd Ave. Beezus is seen going to Grant High School, which is a real high school located about 1/2 mile south of Klickitat St. and 33rd Ave.
John Corbett and Bridget Moynahan both appeared in the HBO series Sex and the City, where Corbett plays Carrie Bradshaw's boyfriend Aidan and Moynahan plays Bradshaw's ex-boyfriend, Mr. Big's wife, Natasha.