Can I fix this?

[umpire99]

FED game. R2, 1 out. B1 hits a "blooper" down the left field line. As the ball falls into fair territory close to the line I have a brain fart and signal foul. As F7 picks up the ball and starts to throw home to try to get R2, I see that he is looking in my direction and does not throw. At this point I realize that I am pointing toward foul territory. R2 scores and B1 goes to second. The defensive coach comes out and wants me to do something about my mistake. He is telling me that his players can't be penalized for me making the wrong call. I told him that I had no way of knowing if the runner would have been thrown out at the plate. Could I have done something to fix this? The defensive team ended up losing the game in extra innings.