The Astronaut says that he was trapped in space because he wished the his brother had never been born, making it so that he could never finish the game. However, since his brother was the one who found the game and convinced him to play it, had his brother never been born he would never have played the game and thus would have been back on Earth.
shareThis is a pretty common paradox explored in any time travel scenario. I don't think it is technically a "plot hole", as this plot merely explores the concept that he wished his brother's existence away, yet in this scenario the force driving the game board allowed his time line to still involve playing this game. Therefore, without his brother in existence to win the game, he was never able to finish.
shareMy take, just off the top of my head:
-The astronaut must have found, or been presented with, a way to travel back in time, and went back to the time when he was playing the game, before he wished his brother away. This time his presence and pleadings softened Walter's feeling toward Danny enough that he didn't wish him away.
-And since it was on the second wish that he reverses the brother wish-away, maybe that second wish was the one that deleted Danny in the astronaut's past.
-Danny appeared in duplicate for a bit, but it was not really necessary--it was only necessary for Danny to continue being present beyond the point in the past where he disappeared. But Danny's unnecessary double did serve the dramatic purpose of showing us who the astronaut was really talking about.
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The story is king.
You assume that there's only one timeline. Then this would be a paradox and no plot hole.
But there are other concepts of time too. Much interesting ones than the lame one timeline one.
The plot hole is actually that they never explained the existence of the older Walter in the first place.
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Lincoln Lee: I lost a partner.
Peter Bishop: I lost a universe!
They never really explain it... but the GAME shot out the car to 'rescue the astronaut'. So either there was another timeline as created from the first wish, and the timeline was created BY the game itself correcting a past wrong or...
The game PICKS who the astronaut will be between the two players. To add another chaotic factor in the game. Everything that seemed created BY the game seemed to 'stay' even after it was introduced except maybe the meteor shower and shooting stars. The older brother, the robot, Zorgons, etc... everything in a real sense was PART of the game, until the game was over.
3rd generation American from a long line of Gottscheers... it was Drandul, dude!