I record them as video, convert the video to a gif, and cut out unneeded frames and resize as necessary.
As for the bouncing, yes, it's intentional. They're colliding with a separate object specifically made for directional reversal, since there have been tons of bugs of them getting stuck in walls. It may or may not be kept that way in the final, since it works seamlessly as-is.
Silly me, I didn't post the inversion effect on the stage itself!