NOBODY questions Dr Who.
How many times have he or she gone to the future?? In some cases the Earth is fine and others it's a mess.
How many times have he or she gone to the past? Where their action helped get folks killed? Isn't that changing the future? Wouldn't that erase a descendant?
Power Rangers.
How does SPD and RPM co-exist? Or the Dino Charge Rangers weren't their Earth destroyed during Ninja Steel? And don't dinos exist now on their Earth?
Star Wars
How does all these books fit in between Star Wars to Return of Jedi?