Plot hole: Servalan & Egrorian discover their Orac is a fake when it continues to light up and make noises after the key has been removed. But this makes no sense; the key functions as it should during the demonstration. Even if it's to do with no longer being connected to the real Orac, with the shuttle getting further away it shouldn't function at all.
Plot hole: The drama on the crashing shuttle comes from the idea that a speck of Neutron material is super-heavy. Yet in the laboratory, Egrorian states that 8 Neutrons make up the core of the Tachyon Funnel. This would make it so heavy it would probably sink through the entire planet, yet Pinder, Vila & Avon wheel it about like the aluminium prop it is. And if the Neutrons are held in some sort of anti-gravity field, that would require an enormous amount of power, but Pinder uplugs it at Avon's request.