Correctable error?
 

R1, R2, 2 out, 2-2 count. R2 asks BU what the count is and the BU says 3-2. So, R2 goes with the pitch (thinking it's 3-2), which is a ball, and gets thrown out at third.

Offended team wondered if we could send the runner back and nullify the out due to the error of the umpire giving the runner incorrect information. I did not think this was correctable by rule, so we let the play stand and ended the inning.

Not correctable.

players and coaches are responsible for knowing game situation. Unfortunate that ump gave incorrect info but does not absolve players and coaches from knowing.

A better approach (at least most times) is for BU to ask the PU to give the count (or tell R2 to ask PU).