I think the "Prototype Hyper Drive" is way overpowered. It is available at the very start of the game I believe, without requiring any research. It gives your ship +5 movement, when drives at the end of the tech tree don't even give that much, has a relatively small mass, and is inexpensive. The only drawback is that it requires 2 units of Antimatter.
Why is something so cheap and powerful available without any research?