Do we see the villains freed before Superman turns back time (if he does)? Do we pick up on the missile only after "Maybe... if he's lucky?" I kind of like the idea of 1 ending with "FREEE!" but then that means the missile took its sweet time exploding (unless we explore the 'parallel time-travelling Superman' idea) and there was no 'double jeopardy' after all.
Separate topic: Miss Tessmacher. Now that we have an alternate jailbreak sequence on the Donner disc, how about using it at the end of 2? Maybe after the credits?