"Okay kids, this is where it gets complicated."
IN THIS ONE... The TARDIS lands inside itself, leading to temporal shenanigans.
REVIEW: The two episodes are so short (about 4 minutes each), neither feels like a complete story. In fact, Space ends on a cliffhanger. So better to discuss them together. Now, we've seen a TARDIS inside a TARDIS before (The Time Monster, Logopolis), but never inside ITSELF. Similar Russian doll/Portal tricks nevertheless resulted. Best not look at it too hard. It's just funny business for Comic Relief, playing on space loops and time loops in a clever way, with lots of hand waving. So for example, the exposition and technobabble solutions only exist inside the time loop. Amy simply repeats what she heard herself say, with no one but herself to give her the answers. The Doctor picks the right lever on his console the same way. The information doesn't actually have an original source. Silliness.
Where the mini-episodes fail, to my mind, is in the sex-related humor. It's like Moffat is back to writing Coupling (which I loved, don't get me wrong). I realize he's poured on the innuendo in previous episodes (River Song is an innuendo MACHINE), but here the story is so brief, it's too high a percentage of the content. And the sex jokes are so obvious and in your face, I'm not sure they're appropriate for children of all ages. The TARDIS' accident is a result of Rory looking up Amy's skirt (and let's talk about that for a bit), and as soon as there are two Amys in the same space, we're inevitably drawn to threesome references. It doesn't help that Amy is apparently hot for herself (and she's never looked in a mirror before?). In Amy's sexual orientation on a wide spectrum, or is she just torturing Rory with sex fantasies? Or rather, why am I even made to ask those questions? In a piece of fluff for a comedy show (The Curse of Fatal Death also had lots of sex, for example), it may have seemed fine. As part of the canon, it feels a little sleazy.
REWATCHABILITY: Medium - Fun, if brief. I'm just not sure about the tone.