So I just asked for a printer version of my letter of rec from a teacher (classified as “Other Recommender”) and I noticed he messed up some information. I have him a resume with all of my activities and I have been apart of STEM Club for four years and Mock Trial for two but he flipped those years to be inaccurate. What he wrote does not reflect what is true and on my application but I just now noticed and all of my applications have been in for months. How much will this affect my application? Should I email my schools or ask him to contact admissions though decisions have mostly been made? 
It’s an honest mistake and I wouldn’t draw attention to it. It’s not going to matter.