Other stuff to take to the track:
- Camping Chair. Most tracks don't have infield seating.
- Water or Sports drink. You don't need a $5 bicycle water bottle because it doesn't have to hang on your bike. Any non-glass container will do.
- Picnic blanket. If you don't want a camping chair. These are easier to pack/carry than a camping chair.
- Snacks. You don't need $2 Clif bars that are designed to be portable on long rides. Bananas, jar of peanut butter (plastic jar), etc... are fine.
- Toilet Paper :D (maybe just leave this in the car just in case).