One question here is asking "What counts as ground for Tenser's Floating Disk?". The query seems aimed at using levitative powers or effects on whatever object the Disk is floating above.
Since certain powers are limited by weight capacity, this brings up the question of how much weight is applied to the object underneath the disk.
The lowest maximum capacity (Arcana check of 9 or lower) for Tenser's Floating Disk is 250 pounds. The maximum carrying capacity of Far Hand is 20 pounds.
Could someone use Far Hand to lift/move an object underneath a 250-pound-full Disk, and through doing so lift/move the Disk itself? How about the same, where the Disk is filled to its full upper limit (Arcana Check of 40 or more) of 2,000 pounds?
Or, how about a different situation. A Riding Horse has a maximum towing capacity of 1,312 pounds. Could it tow a cart that contains a fully-loaded one-ton Floating Disk?
Or, perhaps an unstable surface? Say the support structures under a certain surface will only hold up to 500 pounds before collapsing. What happens when one-ton full Floating Disk crosses over this surface?