Its a common goof, but however small always breaks the film "spell". One of the mourners makes the classic mistake of looking directly at the camera, just after the punch up at the wake, but the real beauty of it is that it's as if she forgot they were filming (so "into" the role), and was surprised to see a camera in the room, check out the double take at the camera, then swift realisation of her GOOF and aversion of the eyes away! Luckily the tall baldy chap is acting so well most people miss this goof.