Trying to remember a movie title. There are children that If I remember correctly go to a sewere and end up in a story like world where there are pirates, princesses etc. I think they followed their runaway dog to the sewere / magical world. The animation isn't that good and is quite simple. So is the voice acting and in fact all of the sounds.
In the magical world there is a flying machine that makes a funny repetetive noice while flying.
At one point the pirates fire their cannons to the princesses castle and she is screaming at them to stop.
To be honest, I don't remember anything else about the cartoon. The siblings find each other and their dog in the end and get to return to the human world through the sewer I think?
Hope someone figures it out since it has been bugging me and my brother for ages!
I watched it in the 90's from a self recorded VHS.
