The Empire of the Rising Sun's lack of a dedicated aircraft production structure unlike the other factions and reliance of Transforming Mecha units (Mecha/Jet Tengu, Striker/Chopper-VX, Sea/Sky Wing) for air power instead may appear odd until you realise that the Empire is based on Imperial Japan, which did not possess an independent air force and which instead maintained two air forces under the command of the Army and the Navy respectively.
Though the United States Air Force didn't achieve independent status from the Army until 1947, either, so Imperial Japan wasn't alone among the major belligerent powers in World War II for not having an independent air force. That said, the US Army Air Forces had wrested a substantial amount of independence from the Army, while its Japanese equivalents were on a much shorter leash.
The United States doesn't seem as powerful as they were in Red Alert 2. In the Imperial Campaign, Los Angeles is invaded and America is subdued as early as the end of the second act. Perhaps Cherdenko's plan did work after all, but it only hit the Americans the hardest.
That, and Ackerman is easily replaced by an Imperial android spy.
The Mt. Rushmore mission: The President states that if his heart stops, the weapon will fire. Given he wants to fire the weapon anyway, why can't the order simply be given remotely instead of driving to the firebase, since there must be some kind of transceiver that monitors his vitals?