During Kara's first number at the Firefly Club, she purses her lips and blows a kiss to someone in the audience. It is an obvious lip-sync as she is still heard singing while doing that.
At the Firefly Club, before Kara comes on, there is a fanfare then applause, but nobody in the audience is seen clapping.
At about 00:59:00 when Kara tells Richard to go away the boom mic shadow moves on the back wall.