While making a small concept, I realized that if you have a locked hopper (A hopper that is powered by a redstone signal), then throw an item on it, then unlock the hopper (Stop the redstone signal), the items that were on the hopper before won't be sucked into the hopper, while new items will.
What I expected to happen was...
The hopper would suck the old items in.
What actually happened was...
The hopper only sucked new items and didn't suck the old items.
Steps to reproduce:
1. Place a hopper.
2. Lock it by powering it with a redstone signal.
3. Drop some items on top of the hopper.
4. Unlock the hopper by stopping the redstone signal.
5. The items from step 3 won't be sucked into the hopper.
Here's a video showing off the glitch: https://www.youtube.com/watch?v=776QfTz7j1U&feature=youtu.be