Spoilers ahead

Rating: Null/10 (28 April 2019)

I really enjoyed the movie but it left me thinking this two thoughts...
How are Nebula and Gamora alive?
When Present Good Nebula shoots Past Evil Nebula, shouldn't Present Good Nebula cease to exist, like the photograph in Back to the Future? Alternatively, if it did happen to Past Evil Nebula, then Present Good Nebula should remember it, and in turn that memory would've been downloaded so Past Evil Nebula would see the hit coming.
And don't get us started on how there's now an alternate version of Gamora.
How did 2014 Thanos send his ship to the present?
There's a scene where Nebula hands over a vial of the Pym particles to Thanos, but the Avengers all seemed to need those snazzy white suits to travel through the Quantum Realm. Why is Thanos' ship different?
Also, if Nebula handed her one and only vial to Thanos, how did she get back? Or if she used that final vial, how did Thanos go forward in time?