There are a number of errors; the pulsars approaching Earth are depicted as cylinders, with a visible rotation. In reality, the gravity field of a pulsar, also known as a neutron star, is so strong (not quite enough to be a black hole) that it can only be spherical in shape. Pulsars were spoken of as theoretical constructs, not only by the people of the doomed world, but by Arturo and Quinn; in this world, presumably the Sliders' home, pulsars were first identified in 1957. The plaque on the Voyager probe shows the location of Earth relative to pulsars. Even though their bodies are small, pulsars are so massive (an asteroid-sized pulsar actually has more mass than the sun) that there could never be a cluster of them - their gravity would coalesce them into a single body at that distance. Finally, the effects of the gravity of a pulsar entering the solar system, even if it was a hundred million or more miles away from the Earth, would disrupt the orbit of every planetary body, including asteroids and moons, to the point where Earthly life would probably die out long before a collision could occur.