5 Reasons People Are Talking About Britney Spears' Vegas Show

Jan. 3, 2014 -- intro: Britney Spears kicked off her two-year residency at Planet Hollywood Resort and Casino in Las Vegas, drawing raves from those who were lucky enough to score tickets. According to Spears, 32, the praise is well-earned, as she worked hard with choreographers to learn difficult dance moves. "They're new, up-and-coming fresh guys, so their stuff is really hard," she explained. "It's more rewarding after you perform something that's really hard to do than just something that you just kinda throw together."

Here's a few notable moments you might have missed if you weren't in the crowd.

quicklist: 1title: A-List Supporters Galoretext: If you weren't in the audience for Spears' first show on Dec. 28, you missed a number of big star sightings: Miley Cyrus, Katy Perry and Selena Gomez were just some of the big names who were in the crowd. "@MileyCyrus Love you so much! Thank you for coming to #PieceOfMe! I adore you :)," Spears tweeted afterward. She also reached out to Perry: "@KatyPerry Was SOOOO good to see you again girl! Glad we could make our Vegas date happen :)"

quicklist: 2title: A Wardrobe Malfunctiontext: During the Dec. 30 performance, Spears was performing her song "Circus" when the back of her dress flew open. But the singer kept right on dancing and singing through the mishap.

quicklist: 3title: Audience Participation (in Bondage)text: For her song "Freakshow," Spears relies on a male member of the audience for the big number. The first night Mario Lopez was brought on stage, and another night, her boyfriend, David Lucado, with whom she talks children, was tapped to perform.

quicklist: 4title: She's Been Accused of Faking More Than Just Singing text: Not only has Spears been accused of lip-syncing throughout the show but recently critics accused her of painting on her abs. Others have defended her. "It's actually pretty insane how much different she looks in person," one fan wrote on Instagram. "She's flawless."

quicklist: 5title: She Performs All the Hits text: Want to see her perform her biggest hits from the past decade or so? You're in luck. According to various reports, the 90-minute show is packed with her newer songs ("Work Bitch" is the opening number), but expect to hear "... Baby One More Time," "I'm a Slave 4 U," "Oops! ... I Did It Again!" and "Lucky" too.