Has there been a baitcast reel made smaller than the Shimano Curado 50? 

I think Ryobi made one a decade or so ago.  They do not import to the US anymore.  Quantum had the microlite back in the early 90's that could cast 1/8oz but I think size wise it was bigger than the 50.  I think the Abu 1500c is the same size as the 50.

mr crappie slab shaker. i don't think there's a smaller one.

I saw on another thread a daiwa presso (thanks Gone_Phishin I will borrow your link )

http://www.japantackle.com/Daiwa/Daiwa_Presso_Bait.htm

It is pretty small.

Buck's Mini Reel, 3oz, 1 1/4" x 3 1\2"

mr crappie slab shaker. i don't think there's a smaller one.

I have this crappie bait casting reel on the smallest bait casting rod I have ever seen. I also have the mini spinning outfit to go with the smallest bait caster too.

I have no clue how to use the bait caster other than flipping or pitching it. It's like the older antique baitcasters but smaller in modern plastics.