This is a really good conversion of the original MSX version. Night Knight on the MSX is one of my favorite games, so I was excited, when it was released for the C64, too.
What I noticed is, that in the first level, the bottom wall in the center is missing. I would appreciate it, if you could add it in the C64 version, so that they are the same. I haven't found any other big differences yet.
The picture shows level 1 on the C64 (left) and MSX (right).