Question

What unusual event does jonas remember in chapter 3 in the giver

Answer 1

I think the answer is that Jonas remembers playing catch with Asher using an apple. Then for a split second sees a change in the apple. 

Answer 2

Jonas remembers playing a game of catch with Asher with an apple. He then sees how the apple has changed. He took it home to see what was different about it but couldn't find anything.