What are some examples from Act II in The Crucible that give clues as to what may happen in the future?
The original question had to be edited down. I think that one example of a dramatic moment from Act II that gives a clue as to what may happen in the future would be Proctor's response in the Act's closing. From a tepid and very distant Proctor at the start of the Act, the closing is one in which Proctor is shown to be intent on ensuring that good triumphs over evil. The ending to the Act in which Proctor assures Mary, and the audience, that he will not let Abigail win is one of absolute defiance and intensity. This is reflective of Proctor's own emotion and personal belief system that becomes evident in the final two acts of the drama.
I think that another example of how events in Act II will foretell the rest of the drama is the sudden rise in arrests in Salem. The driving force behind Act II is that Salem has moved into a realm that is out of control with all the accusations and arrests based off witchcraft. What started out in Act I as something isolated and almost trivial has become deadly serious as the entire town is completely overwhelmed with accusations of witchcraft. This is reflective of how the trial in Act III will function and the fundamental trajectory of the drama. The childish actions of the girls in the first Act have become deadly serious in Act II and will continue to be regarded as such as the drama continues.