I've been working on a level, but the strangest thing happens


I push a keg into some water "miles" away from a Rainbow Spirit. When the Spirit reaches the same horizontal line as the keg in the water, the Spirit and the keg blow up. The spirit is gone, but I can still walk on the keg. This is an undesired effect in my level. Can anyone help me figure out why this is happening, and what I can do to avoid it?
A test level is attached so you can see my problem for yourselves.
Thanks,
Mette