Why did the old man trip Lucy/Sarah?
During Lucy's first "job," when she's in the white outfit, she's pouring brandy with the ladies. When she gets to the last old guy, she turns around and he grabs her leg and makes her fall. Another older man - presumably the host, who spoke about one of the dishes - politely helps her up as if she's simply stumbled. The other women look on, not seeming to acknowledge that the man tripped her at all, yet everyone had to have seen it.
What was the point? Why did he trip her? And why did everyone else act like she'd simply fallen?