In Maria's first appearance, and again in this one, it is established that she only speaks broken English, and not very well. When Manuel talks to her on the phone, however, he speaks to her in English, when Spanish would be easier for both of them.
Rob's dialog with Maria on the phone indicates that she uses the word "amigo" for Manuel, who is either her boyfriend or her fiancé. "Amigo" is not used for either such relationship. It means a platonic friend (boyfriend is "novio," fiancé could be "novio" or "prometido").
The choreography of the chair ramming into Rob is too gentle and controlled, making it impossible to believe it could crack or break his rib in any way.