Deliberate mistake: When Gulliver is first placed in the dungeon, he is attacked by a tiny seagull, however comparing the size of the bird with Gulliver's foot, it appears to be about the size of a fully-grown Lilliputian. This was obviously done deliberately as a correctly-sized seagull would be far too small for the joke to be effective.
Deliberate mistake: At the beginning of the end credits, the newspaper article just repeats itself. Plus, it has a weird shift of going from a first person account to a third person review of the original book (including mentioning George I was King of England at the time of the writing of the Travels).
Answer: Obviously, it's just a deliberate error in a fantasy film that is full of plot-holes and errors. They certainly aren't anchor lines, as the ships are actively involved in a military engagement (surrounding Gulliver). Also, no navy flotilla of sailing ships would have lines hanging loose at the bow or stern, particularly going into a military engagement. Rather, the lines would be coiled and neatly stowed on deck. In this case, the deliberate error permits Gulliver to tow away the Blefuscudian ships in just a matter of moments (even though Blefuscu is over a half-mile away by water).
Charles Austin Miller