A reality show may have let the cat out of the bag on Jennifer Aniston's wedding dress ... and nobody noticed.
It went down on an episode of "Say Yes To The Dress," where a fittings specialist at Manhattan wedding dress institution Kleinfeld revealed she picked out an $8,400 Mark Zunino gown for Aniston's wedding.
The episode aired back in April.
We reached out to Kleinfeld ... no word back yet.
TMZ broke the story ... Aniston and Theroux tied the knot earlier this month.