What if the rule was created after the tank was already in the park? There was no information given on how the tank was transported to the park, and you're creating a violation based off a hypothetical.

Are you being serious? Obviously the rule is not meant to outlaw that specific scenario and local authorities or the company that provides the transport will put measures in place to make sure it goes safe and sound; they will close the park, drive at walking speed, etc...

Maybe a huge crane lifted it into the park from outside the park. Would the crane be in the park then?

What if it's fired from a cannon and lands in the park?