The 23-year-old actress, who will be next seen in "The Amazing Spiderman", wore a red couture dress which got ripped just below the fastening zip, reported Ace Showbiz.
The beauty covered up the tear with a patent maroon coat as she arrived at a bar to carry on festivities.
Actresses Rashida Jones and Leslie Mann were helping her with the attire just before her dress malfunction.
She was joined by Lanvin designer Alber Elbaz, who was shocked to look at the rip in the apparel.