After a promising performance from Falkirk that saw the Bairns dominate the majority of the game, it was Rangers who snatched two goals late on with goalkeeper Cammy Bell pulling off some fine saves.
"The performance was not as good as we had hoped, that goes without saying," McCoist told Sky Sports News.
"I cannot put my finger on why it is not quite clicking, because we have got good players. We can and we will do better."
The win against Falkirk saw McCoist's side bounce back after losing their opening game of the season to Hearts last weekend.