When on portrait mode, on my Samsung Galaxy S4 running Android 4.4.2 and Chrome (latest stable) I noticed a bug when moving a thread be it through the forumdisplay page or the showthread page. When you're on the Move Thread overlay, choose the destination node and you'll notice that it doesn't change. You have to switch to landscape mode and then you'll see the new destination changed properly on the form.
Also there is an inconsistency here. When moving a thread through the forumdisplay page there is an additional checkbox that you have to click if you want to add a prefix. However when moving a thread through the showthread page there is no checkbox and you can simply assign (if you want) a new prefix to the thread. Imho the latter is the best approach and the former should be discarded because it makes things more complicated.