When monsters are stuck on platforms, all the actions that the monster makes are stored in a queue. When the platform makes a stop (not very often in the case of the Ketchup map), Marathon dequeues the first action in the queue. So, the queue gets filled up with a bunch of attacks, and, because of the way Marathon handles the attacks that are on queue, all of them are released at the same time. In case anybody cared...
: Somewhere in the archives there is a battlecat film/map.
: The idea is that if a platform goes too fast, the attacksequnce gets uhm,
: on-hold.
: When the engine/monster finally gets to shoot his load... er, well,
: the effect you described, a sudden burst of the accumulated attacks.