Seriously? You couldn't just open the case to get the helmet? Had to shatter it all over the place?
That was to show he was upset.
I am just surprised they figured it out like that. Was expecting a big reveal in person next time they met Zoom.
And it can't be simply 'Jay is Zoom'. We saw that there were two Jay's at the end of that episode. They didn't see that.
I don't think even Zoom is fast enough to be Zoom on E2 and Jay on E1 at the same time.
I think the hint is that girl - she seemed to have two personalities. Maybe Jay was able to split himself?
The good Jay seemed not to know who Zoom was, or at least was a hell of a good actor pretending not to know. But Wells (Thawne) did it in season 1 for a long time so who knows.
Plus the Jay on E1 certainly had no speed, unless he was able to fool the scanners into thinking he was powerless.
But I can't see Zoom pretending to be a nice guy and all helpful just to fool them. There would be easier ways.