Headscratchers / Bloons Tower Defense

• The amount of Depth Perplexion in these games is, well, perplexing. Take the Monkey Ace for example. It's flying above the bloons, yet its projectiles can still hit them. There are three possible ways to interpret this, all of which have their problems:
  • Their shots are angled downwards. But if that's the case, shouldn't the darts get stuck in the ground right after hitting a bloon, instead of continuing to fly in a straight line and popping other bloons in their path?
    • This probably could be the case. The Neva-Miss Targeting upgrade could come from the darts locking on and flying down to chase the bloons. Similarly, the Pineapple Surprise upgrade has a countdown tied to the pineapples, implying that they're falling for a time before exploding. It would make some amount of sense to me if, say, the darts fell to ground level then fanned out.
    • What if every Ace dart has something similar to Neva-Miss allowing them to do this, and the Neva-Miss upgrade itself just takes it up to eleven?]]
  • The bloons are flying at the same height as the planes. Which is also impossible, since the bloons are affected by road spikes, which are at ground level, implying that they're touching the ground.
  • The planes are flying REALLY low to the ground... but they're obviously high in the air, since they can fly over tall obstacles.
    • What if the bloons are really, really tall, and we just can't tell because of the top-down perspective?