You should be fine. There are a couple of jokes that will definitely go over the head of four year old, and probably 8 year old unless someone explains it.
Example: Sinbad is telling a story to the female lead about how he once a knife at his throat, a knife at his heart and a knife at his (he pauses) then exclaims "Pickles and Eggs! Thats what we eat here on the ship. We have plenty of pickles and eggs."
That's about the worst of it. Other than that it was a cute movie. My son(10) enjoyed it.
Have fun!