Did you mean to put 4.7km, the length of the Blue course that you ran?
I don't own a Garmin so I don't know how far I actually ran. I just put the straight line distance in kms and call it miles. I can measure the distances I run from work on the GIS system and ask the guys I train with on a Monday and Thursday who have Garmins how far we've run. When I run from the house on my own I just take a guess at how far I've run based on my usual speed. Not very scientific but it's more to do with the effort I put in.
I ran Brown which was 6.2km and my Garmin recorded 6.46km. Thought it might have been a bit more, but I did pretty run straight on all legs.
You had a great run on Sunday - very impressed. Unfortunately I tried to run straight on a lot of legs but ended up doing loops near the controls!