This Apple support note for Final Cut Pro X and Motion says that the updates require MacOS 10.6.8 or 10.7.4 - no earlier versions of Snow Leopard or Lion will work.
As Motion 5.0.4 is built into Final Cut Pro 10.0.5 (so effects can play, it doesn't have the Motion UI), then this sentence from
the Motion 5.0.4 release note is relevant:
This update also resolves issues in FxPlug 2 where some images were returned at half height or upside down.
This will make it easier for effects developers to fix effects where there are display problems, but few developers were informed about this in advance of today.
On the new MacBook Pro with Retina display (MacBook PremiAir?) machines, some plugins that use images for on-screen controls might not display properly.
Developers were only told about 10.0.5 and the small extension to the way plugins are coded to support the new hardware and software 4 hours ago.