The Rescue Mission

1. When it received an alien distress signal, Terra Venture was somewhere between 5.6 and 14 light-years from Earth (based on Destined For Greatness and The Lost Galactabeasts, Part 2, respectively); as the visual of the alien ship showed the ship approximately 32% of Terra Venture's total course, with Terra Venture's location implied to be fairly close, then the total distance between the Earth and the Eurolean Galaxy would have been roughly between 20 and 40 light-years, which wouldn't have been nearly enough distance to escape the Milky Way, let alone the 80,000 light-years to our nearest galactic neighbor.
2. As Leo and Mike were trapped beside an open doorway leading into the vacuum of space, the heliship flew up with its side near the open doorway, and the side door flipped up, not experiencing a vacuum as the alien ship was.
3. Leo and Mike were able to leap across the void, landing safely inside the heliship.