By beaming a huge solar - powered laser at a vast ultralight sail attached to a spacecraft, we can use the energy of our own sun to accelerate the rocket to great speeds.
Some of them have a hugebeam of energy down the middle that reflects the merging worlds, so one side of the line is a Mortal Kombat location and the other is a DC location, like Shang Tsung's island and Wonder Woman's home, Themyscira.