THIS QUESTION CONTAINS SPOILERS FOR THOSE WHO HAVE NOT VIEWED THE LAST EPISODE
In the last episode of Fringe, Peter finds a tape addressed to him, which was encased in amber. In this tape Walter says that if Peter is watching the tape, that means he probably got a weird letter from him and decided to go look for him the lab, thus finding such tape.
This tape was there since 2015, when Walter had already sent the letter and inoculated himself to go with Michael to the year 2167. But then something happened, and Walter had to amber the whole thing.
But this means that for the tape to have been recorded, the invasion must have taken place and Walter must have formulated his plan.
Fast forward to the end of the episode, once the timeline is reset, Peter gets said letter in 2015. However, unless I have misunderstood something, this is impossible.
From what I understand, the timeline goes something like this:
- Peter and Olivia in the park with Etta.
- Invasion of the Observers.
- Etta disappears.
- Walter elaborates a plan to prevent the invasion.
- Walter understands he will have to sacrifice himself and go with Michael to 2167.
- Walter records the tape and sends Peter the letter.
- Walter was going to the future, but instead encased it all in amber, and then stays like that for 20 years.
- All the events in Season 5 take place, ending with the timeline being reset.
Since resetting the timeline would modify things from point 2 onwards, how could Walter have sent Peter that letter? He could not have sent it (and recorded the tape) before the invasion took place.
Am I missing something or should we assume that the Walter in the future thought about this later and found someway to make the letter and the tape 'appear' in 2015 (in the reset timeline)?