Thanks for reporting! You’re correct to be suspicious of the extra yellow segment - it certainly doesn’t belong.
Review mode is showing how your trace compared against other traces submitted by other Eyewirers. Please remember review mode isn’t always the final answer. In this case, the first player probably accidentally added that yellow piece. Since we are a consensus based system, the third player who played after you (you were the second player) agreed with your trace and did not add the yellow piece. As a result, the cube’s consensus no longer shows that yellow piece. Your accuracy should reflect this update as well.
You can check that past 60 cubes that you played by looking at your activity tracker in the upper right next to your username. Cubes that you trailblaze or have a weight of 2 may change accuracy as other players play the cube. Your review mode for a cube will update too!