Britney Spears' 5 Biggest On-Stage 'Oops'

March 4, 2009 — -- Britney Spears' "Circus" is chugging along, but not without its fair share of setbacks and slip-ups.

The pop star's first tour in five years has been punctuated with "oops, I did it again" type moments worthy of their own blooper reel. The latest: an overzealous fan stormed the stage and tried to shake it with Spears at her Sunday night show in Connecticut, sending security guards into a frenzy and racking up an arrest.

With the news that Spears is expanding the international leg of her tour beyond Canada and London (where she's reportedly requested a stripper pole in her hotel suite for off-stage workouts) to Sweden, Germany, France and Russia, it seems an appropriate time to assess what mistakes Spears might want to avoid as she greets her global audience.

Below, ABCNews.com takes a look at four major mess-ups from Spears' "Circus" tour thus far and as a point of reference, looks back on one of the biggest blunders of the 27-year-old pop star's career.

Spears concert-goers play by her rules, and that means no smoking -- or else she stops the show.

The pop star left the stage for half an hour at an April show in Vancouver, Canada, apparently because of smoke in the audience. Spears stopped performing about 15 minutes into her show, and an announcer told fans to put out their cigarettes, some of which may not have been of the tobacco variety.

Upon returning to the stage, Spears scolded the crowd, saying "Don't smoke weed." Following the show, Spears' publicist, Holly Shakoor, issued a statement apologizing to fans about the delay. The statement said "crew members above the stage became ill due to a ventilation issue."

Funny -- Spears didn't seem to mind smoke back in July 2008, when she was publicly slammed for puffing cigarettes in front of her young sons.