Are there halachot that get in the way of doing this?
(Most people who do this do it because the tree needs to be kept indoors for the winter. They usually prune it to keep it small and get it to bear more fruit.)
If the pot is not in direct contact with the ground (ie a non-absorbent surface, like a plastic dish, was placed between the pot and the floor), then the laws of shemitta would not apply to the tree, assuming the pot was in E”Y.
Anything that applies to growing plants. For example, if pot does touch earth, and you bring it from once place to another, have you replanted the tree?