For example, if the theory goes that more people will want to buy apple now that the price is a "steal" (people think it's harder to 2x a big number than a small number) then it could go above that on open.
I prefer to believe that stocks are not in a bubble of such epic proportions that a stupid split can be an "event".
That is the split of Google A and C some years back, where Google added a new class of shares with different voting power.
In the Apple split each share after the split will be worth 1/4th, have 1/4th voting power, will receive 1/4th of dividend, etc. just reading happens in smaller fractions.