Spoiler Below I was surprised Bloo's Spinal Tap "pod" opened so easily!
I missed some parts of the episode, but I liked it. It seems, however, that season 5 is big on pop-culture/throwbacks* - and short on originality. This one is a good example.
* by throwbacks I mean referencing previous episodes - for example, Mac's sold "Star Wars" (Space Wars? whatever) showing up in the flea market.