While I can't by any means disprove it, that strikes me as unlikely. The Normandy is almost twice as large as the Space Shuttle. Assuming it has similar density, it's mass would scale from the Space Shuttle's 2,030,000kg to 3,720,000kg. To shunt that to Andromeda within a 24 hour period (which it must have been as the crew haven't started to death) , a distance of 2.5 million light years, would require 820,000,000,000,000,000 Newtons of force. That means 1.9*10^40 Joules. An atomic bombs gives something in the range of magnitude of 10^13 joules. It would take something like 1,000,000,000,000,000,000,000,000,000 atom bombs to propel the Normandy to Andromeda. Not to mention it would be traveling at 5.5*10^17 m/s when it got there. That's not the kind of crash you survive.