"1969" was a predestination paradox. Everything that happened in 1969 had already happened when they left 1999 at the beginning of the episode. That's why Hammond gave Carter the note, their way home.
time, definitely my favorite episode of sgu. i love how it begins with you not really knowing why the screen is the way that it is. and of course the ending which deletes the whole thing. plus the serious stuff with eli, and funny things like the movie list. and the part when eli goes "what the" (commercial). and yes i've seen the ep many times.
Before I Sleep