Complex sentence: Once in space, Rex asks R2-D2 to make the jump to lightspeed as well, but accidentally overshoots the ship's hyperdrive, and passes the Endor moon, and instead gets caught inside a comet cluster.
Split into simpler sentences: Once in space, Rex asks R2-D2 to make the jump to lightspeed. However, the ship accidentally passes the Endor moon and instead gets caught inside a comet cluster.