This is quite an old question as has been alluded to already. It would not be the visulisation of the surroundings that much to do with the behaviour of your spacecraft. If it were just this you could be anywhere and simply close your eyes for the same effect :-) However I am sure this was not what was intended to be meant but more that you were to imagine that you and your craft were, effectively, the whole of matter within a (maybe) flat universe. As Lee implies, this may not be a possible allowable configuration with any physical validity, anymore than trying imagine the sound of one hand clapping. Nonetheless I suppose we can theorise (guess?).

In Quantum Electrodynamics (QED) Feynman proposed that action at a distance (fields) could be the sum of all interactions between objects in the universe. To get around the limitations of the speed of light he proposed a (normal) retarded wave and an advanced wave (going backward in time). Summing the relative effects of all these interactions gives a concept of inertia being related to all the other mass in the universe and potentially giving justification to Mach's principle. He only did the calculations for very simplistic cases, with some success, but I think got bored with the immensity of the mathematical task in trying to do it realistically. He believed it should be done, so for aspiring young theoretical physicists there is an opportunity...

The result for the loan spacecraft would be that the laws of physics would have different constants from what we experience in our universe. I imagine that (if it was possible for us or some thinking entity) to exist, that objects would have much less mass (even objects within the spacecraft) or, if you like, inertia. But there would be some because we are not talking about a single solitary particle so all the particles would still be interacting with the others in the craft.

This kind of addresses another thread on the site about what is inertia. It is, according to this theory, related to all the other mass in the universe.