I think it was a deliberate bridging episode between RTD's style of show and his. Quite a lot of it can be said to have been taken from previous RTD era episodes, but the way it was constructed and built was a lot more solider, with nothing being pulled out of a hat at the last minute for just one. Sorta a greatest hits montage almost, to reassure people that it's still the same show, that this is still the Doctor and his world, before going on to Moffat's version. Just as Matt Smith started out that ep in a very-Tennant way, slowly evolving into his own version, I think Moffat deliberately structured the ep the same way.
The full-on Moffat era starts next week. Geronimo indeed!