Well sure. In a lot of these things, like Tippler's time machine, space gets folded in improbably ways, but as Frank Lloyd Wright said when asked how his mile high tower he designed would be built, 'That's a problem for the engineers'. A lot of it requires either exotic materials or structures that might simply not be able to be constructed, but technically, they don't violate the known laws of physics. So they're all based on exploratory physics like string theory, loop quantum gravity, or MOND. Neat ideas that might work and the math is at least partially there, but can't be tested or figured out exactly.
Travel through a wormhole would be through normal space time although highly curved, but things get weird when such things happen. A thought experiment with a black hole and various lightlike paths around it can easily come up with two light like paths that have different distances between the same points. Hell, it's basically happening in every case of gravitational lensing. People mistake things like wormholes as being FTL when they are not really as the path taken through the hole is not FTL, but may be seen as such by observers that can't see the wormhole, although the actual relationship is determined by the properties of the wormhole. This can be taken in extreme with teleportation. If it's possible to teleport between point A and point C, then they must be connected somehow, either either through something like a wormhole, hyperspace, or a transform of some type or every point would be equal to every other point. The typical FTL travel is time travel doesn't hold for such cases because while it might be if it was FTL through Minkowski space using the Lorentz Transform, the actual relationship and qualities of such travel are determined by the qualities of that space or transform that is actually transversed, not of the flat space time between the two points made by a separate observer.