Carey was leaving an after party at popular Los Angeles hotspot Poppy with her boyfriend, Brian Tanaka, when she was asked about the mix-up.
"It wasn't on purpose!" Carey can be heard saying as she heads to her car.
Carey explained what happened on Twitter, writing, "Got caught mingling on the way to the loo during a commercial break.. took the first seat available, happens to be right next to Steven Spielberg ?? Cut to next commercial break, guess who comes back to her seat..."
She concluded the story by writing to Streep, "You can take my seat any time! ??????"