When you view your challenge map you will see other people's avatars on the map as well.
This will never be every single person on the challenge as this would crowd the map far too much. Therefore we have different options of who you see.
Recently Active (Default) - This is approximately 150 random people who have been active on this challenge recently.
Just Me/My Team - No other avatars will display on the map. If you are in a team, you will see your team Avatar, not each of your team mates.
Community(s) - If you are a member of one of more communities you will see each of them here. When you select a community you will be able to see every member of that community on the map. Communities over 150 people will also be filtered to avoid overcrowding the map.
If you do not want other people to see you on the map you can adjust your privacy settings. Find out more about this here.