Fresh from the early evening premiere of his latest project, the comedy Ted, MacFarlane headed to his Beverly Hills mansion where he hosted a private afterparty that began late and went into the wee hours of the morning.
"The party started at 11 p.m. and was still going at 4a.m.," an attendee tells PEOPLE. "Seth had a whiskey bar and a guy rolling cigars for guests, which was pretty cool, and something he hasn't had at his parties in the past."
MacFarlane, who is known to host some of the most highly anticipated house parties in Hollywood, also managed to get some star power on stage during the fête.
"Rumer Willis got up and sang for a bit," the partygoer says of Demi Moore's daughter, who has been showing off her vocal chops lately at Jason Scoppa's Sayers Sessions. "She did a really good job!"
Also on hand was Gerard Butler, who was surrounded by ladies as usual.
"He was with two unrecognizable girls," the source says. "He was definitely acting flirty with them."
Angelina Jolie's dad Jon Voight also dropped by the bash, an appearance the source calls, "very random."
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