have seen that
fun to watch (in a sick way)
i imagine that the loco was fine if cleaned, allowed to dry out and lubed-probably was fine after simply being extracted from the mud and put back on the track ! theres not much in the way of real electronics--electric motors will run just fine when submerged-my sons old battery boats were examples of this-the things will rust a bit if not dried and lubed-but its amazing what they weill take-even cheap motors!
those were the days when LGB was ....perhaps not as precious
stupid kid tricks we all love and know better