Changing gravity for rigidbody in animation

I’m animating some things tumbling through a large glass tube. Part way through the tube they hit an obstruction and bounce around it before continuing on their way. I really don’t want to have to animate the collisions by hand so I turned the whole thing 90 degrees and decided to let physics and gravity do the work for me.

Besides some minor collision issues it works pretty good. Except the speed they fall is way too fast. I want the viewer to be able to clearly see each one hit the obstruction and bounce away. Also it doesn’t match their speed in previous shots. Is there any way to change the gravity for a render outside the game engine?