Dodge announced that the crate contains matching spare wheels and Demon-branded tools. In the trailer, we can see some of the tools, including a jack, impact gun, socket wrench, and a tire-pressure gauge. We imagine that part of the plan is that owners can have an extra set of tires, perhaps some even stickier drag slicks, and have everything on hand to swap them out quickly.
Dodge also revealed that it will include a "Demon Track Pack System" and "Direct Connection Demon Performance Parts." These items present more of a mystery, since the trailer only shows the wheels and tools. One of the official images (pictured above) shows the crate opened up, and what may be portions of a racing harness. So the Demon may include some safety parts that could be installed or removed to make it safe on track, or comfortable on the street for the driver and passengers. Assuming that any passenger seats are left in the car.