We all know reality television shows, including and especially American Idol, are basically serial hoaxes. But couldn't they try a little harder to maintain the illusion? Idol producers went to elaborate lengths last night to falsely present Jennifer Lopez's on-air performance as "live," but they left behind a few editing artifacts proving that it was taped.

Lopez's performance of her new single, "On the Floor," was introduced by her fellow judges and host Ryan Seacrest with a big fat "LIVE" bug in the corner of the screen. Cut to Lopez singing and dancing, with the audience cheering all the way, followed by a commercial break. When the show returned, so did the "LIVE" bug, at which point Seacrest apologized for a brief delay occasioned by Lopez's costume change: "While we wait for Jennifer to change her clothes, we're thrilled to debut a teaser of her next hit." So they played a brief video while Lopez changed out of her stage clothes—because she literally just walked off the stage from the performance that you just saw, get it?—until she returns, still panting and flushed from the workout. "She's back! Congratulations," Seacrest says.

Trouble is, Lopez wasn't back, because she hadn't gone anywhere. She was probably out back having a smoke. As the video above shows—and as a tipster first pointed out to us—her performance was taped and cut together from multiple takes. Note the robotic brace that rises from the stage to steady her while on a raised platform: Sometimes it's there, and sometimes it's not. In the space of seconds, it disappears and returns. Clearly the version that aired was a combination of two different performances, one with the brace and one without. Shoddy hoaxmanship, Idol. We've come to expect better fakery from you.

A Fox spokesperson did not immediately return messages asking about the ass brace, and if the show had ever presented any other taped performances as live.

[Video edited by Matt Toder]