Fire kills the creature. Fine. But unless they were using napalm (and they weren't), how did they keep it out of the water long enough to kill it? You'd think after the first lick of flame, it would submerge and run.
- They drove it into shallow water first.
If the Devil Fish was intended to patrol/defend resource-rich stretches of ocean from unauthorized exploitation, then what plans did Davis/WOI/Woi/whoever have for calling the fish off when someone who was authorized came along? It's akin to releasing rabid wolverines into your auto lot to scare off burglars without any way to get them out once employees and customers arrive!