They can't get there time travel theories consistent.
In this Ror..er Rip says that it takes time for the changes in the past to catch up to the future, yet in the Flash when Eddie kills himself Thawne immediately fades from existence.
Also if Stein changed his past enough so he never met his wife and the ring disappeared, then how did he still remember? And then shouldn't he have also remembered meeting three people who stole his tracker and then visited a space ship in 1975?
I like what they are doing so far, but they need to be more consistent in their time travel stuff.