It seems that dolphins spawn slightly earlier the first time that a level is loaded and slightly later on the retries. In the gif, I am holding y+right. On the first load, mario runs over the plant. On the retry he runs into it. This happens on every retry. It also happens if I move the dolphins x position.
So far I have not recreated with other sprites.
I'm not sure if this is related to the cannon entrance...
Anyone seen this before? Any ideas how to fix?