I Forgot to Hit End Until I Drove Away
That's ok! Slopes added a trim feature because this happens to all of us.
When you're done recording you'll see a "Edit Lifts and Runs" button on the save screen. If you already saved, you can edit your day by hitting the "Edit" in the top right when you're looking at the day. From there you'll be able to remove any lifts or runs that were detected while you were in the car.