The scene also breaks canon from the original movie. In this movie, we're presented with a fact that "Spiketails can't swim" so Spike ends up almost drowning until his adopted swimmer mom saves him. But in the first movie, Spike is seen swimming just fine (in deep water as well) near the end, just before they face off with Sharptooth. So he's fully capable of swimming. I thin he swam in another sequel as well but I don't recall.