Stupidity: When the police turn up the first time the mother lies to them to get them to go away but the burglars can't hear the conversation. She could have told them exactly what was happening and that she had to make it look like she'd got rid of them. She could have then smashed all the cameras and just let them in.
Suggested correction: This was a character decision, and a completely understandable one. Her daughter was being held hostage in the panic room. She decided to cooperate with their demands for the safety of her daughter. Your idea is a solid one, but she simply did not think of it in her state of mind. She opted to get rid of the police, and her decision is not a movie mistake.