The initial design of Optimus' jetpack resembles the booster pack from the original Jetfire (and thus, the FAST Packs from Super Dimension Fortress Macross), and would thus be a reference to another Optimus combining with a Jetfire in Armada. It could also be seen as a reference to the final scenes of More than Meets the Eye, Part 3 from the original series, when Optimus Prime borrowed Sideswipe's rocket pack to chase Megatron's space cruiser.
Now, that's some upgrades...The redesign of the jetpack, while resembling Cybertron Optimus Prime's super mode, is more probably a hint to the Apex Bomber upgrade, as the winged gloves (and the wings themselves) seem to heavily imply.
Ratchet once again harps on the fact that "Autobots can't fly", a common if frequently broken rule throughout most of the Transformers fiction, before being confronted with the harsh reality.
