1. When you zoom out when viewing a PCB, the net labels on pads and tracks get smaller, then disappear, then come back again as you continue to zoom out.
2. In both schematic capture and pcb design, when you click on a toolbar item such as Wire, you can't then change your mind and click on another toolbar item. You are stuck in Wire mode, so every click on the toolbar actually passes through onto the schematic or PCB, drawing wires, or placing parts if you clicked on that option. I've had lots of unexplained items appearing in my designs because of that.