AnnaLynne McCord's cleavage got the breast -- err, best -- of her on the set of 90210 in Hollywood Wednesday.

PHOTOS: Most embarrassing wardrobe malfunctions ever!

The 24-year-old actress looked devilish in a figure-hugging, low-cut red dress while shooting scenes for The CW series' fourth season. The only problem? McCord inadvertently exposed her nipple tape on numerous occasions.

VIDEO: McCord's costar spills 90210's biggest secrets

Later in the day, McCord -- currently dating Prison Break star Dominic Purcell, 41 -- changed into a more demure striped maxi-dress. While her chest was fully covered, the see-through fabric accidentally revealed her underwear.

PHOTOS: Beverly Hills, 90210 stars, then and now

Despite McCord's multiple wardrobe malfunctions, the actress remained chipper, asking her Twitter followers to support her new onscreen love interest, Justin Deeley, 25.

"Everybody send some love to my cowboy Justin Deeley and tell 90210 to let me keep him forever!" she wrote.

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