I forgot to stop recording
It happens to the best of us. You get into your car to drive home, you forget to stop Slopes, and then your top speed and the Friends Leaderboard get all messed up. It's an easy fix though!
First of all, open the recording from the Logbook, and at the top of the screen you'll see Timeline, Compare, Share and three dots for more actions - tap on the dots → Edit.
Then, tap on Timeline Editor under Tools.
In the Timeline Editor you get full control over the recorded data. You can easily add, remove, or tweak any detected lift or run. So for example, tap a lift / run when you started to drive away and hit delete.
You'll be prompted if you want to delete all lifts / runs after that point, and you can say yes. Hit Done, then Save, and you're good to go. Your stats will update in the Logbook, and will adjust on the friends leaderboard too.