Factual error: When Joseph Sedley presents Becky Sharp with the parrot, he says it is because she loves all things that come from India. The Blue and Gold Macaw, however, is native to South America. (The director's commentary makes it clear that she is aware of this. (She could hardly not be, coming from India.) It was a bit of "poetic license.")
Factual error: Heavily pregnant at the time of filming, Reese Witherspoon is obviously pregnant throughout the film. She's less pregnant in the scenes where her Becky Sharp character is pregnant than she is many others.