When Bonzo is marching with the Salamander army and his cadence as they march to the game... when he gets onto the platform it is clearly visible that he is still singing the cadence but his lips do not move.
Colonel Graff remarks that Napoléon Bonaparte "conquered the known world," which is absolutely untrue. First, in the time of the Emperor Napoleon I, the basic coastal geography of all continents except Antarctica was already known, so "known world" is a tautology in this case. Second, although Napoleon conquered a large area in Europe and briefly controlled some colonies in the Americas, his realm at its furthest expansion was only a small part of the whole world. Its strength lay in its population centers and trade routes, not its square mileage. It never matched the size of either the British Empire or the Russian Empire, both of whom were his frequent enemies. Napoleon's obsessive attempts to cripple those two empires backfired on him and led to his downfall.
In Ender's first team, in several different sequences during the movie when the team is at attention, the blonde girl on the left side and the black girl on the right side appear and reappear within the same scene.
When Ender and the others are launched into space to go to Battle School, huge clouds are shown (very realistically) moving outward from the launch area as the ship rises, similar to scenes of the Space Shuttle or the Apollo Saturn V taking off. This isn't exhaust from the rocket; in order to prevent (mostly acoustic) damage to the trench underneath the rocket, thousands of gallons of water are poured into the trench, and this is turned into clouds of steam by the rocket's engines.
However in the film, the rocket is seen to be tilted into a vertical position above a large circular opening into which the engines will fire. There is nowhere for a water deluge to pour, or really any need for it.
The launch acceleration is much too high. It appears to be about 6g, which would probably have caused a number of the cadets to black out. The Saturn V that launched the Apollo astronauts reached a very brief peak acceleration of 4g with the 1st stage. The other stages didn't produce more than 2g (stage 2) or 0.75g (stage 3).
The goof items below may give away important plot points.
After Bonzo breaks his skull, in the close-up shots, the edge of the shower stall is at the middle of the back of Bonzo's head and there is several inches of space between Bonzo's shoulders and the edge. But in the long shots, Bonzo's entire head is lying on the shower edge and there is no space between his shoulders and the edge.