Revealing mistake: In the scene during Ivy's sister's wedding ceremony, right after the people all notice the boys screaming "Mr. Walker, Mr. Walker" Ivy is walking with her arm extended in front of her to find her way through the crowd of rushing people. At one point she has her hand right in front of a man's face (he has a beard and mustache), and despite being blind she then brings it up over his head and behind him in perfect timing without ever touching him. (00:14:15)
Suggested correction: This is because Ivy explains in the movie that people give off a faint color to her. She knew it wasn't Lucius so she avoided him.