Balotelli, a half-time substitute for Lazar Markovic, had a quiet day after coming off the bench, until he raced onto a long ball in the 88th minute and slotted past Shay Given in the Villa net.
The flag was raised for offside, though, and the score remained 2-1 to Villa, ending Liverpool's hopes of claiming silverware.
But replays showed Balotelli was clearly onside when the ball was played and the Italian took to his Instagram account to vent his frustration.
Posted alongside a photo of the incident in question, Balotelli said "the picture says it all", before going on to congratulate Villa for their victory.
Balotelli has a history of controversial social media posts, having received a one-match ban for an Instagram entry in December that contained potentially offensive language referring to "ethnic origin and/or colour and/or race and/or nationality and/or religion or belief", before hitting out at critics in a strange video posted online in March.
