A member of the Olympics opening ceremony cast managed to take part in the athletes' parade alongside the India team.
The woman was one of the volunteers who had been part of the cast of the show and became "over-excited", according to Lord Coe, the London 2012 chairman.
He said: "She was a member of the cast who got slightly over-excited, we had suspected she was probably a member of the cast but she clearly started in that venue and we will be speaking to the Indian delegation about that.
"She shouldn't have been on the parade and we will look into that... the next time we have an opening ceremony."
The young woman, clearly dressed differently to the Indian team in a red shirt and blue trousers, walked alongside flag-bearer Sushil Kumar during the parade.
India's chef de mission P K Muralidharan Raja said: "She had no business to walk in with the Indian contingent and we are taking up the issue with the organisers.
"We don't know who she is and why she was allowed to walk in. It is a shame that she was with the athletes in the march past."