The usual suspects

At the end a man in a trilby shoots keaton and then drops a cigarette butt and sets the whole ship ablaze.

Just a couple of seconds before verbal is shown on the dock, he isn't even on the ship.

Freeze frame man in trilby and you will see it is not verbal.

This is why I am puzzled by it.

The surviving Hungarian, severely burned and hospitalized, describes to a sketch artist a man he saw during the attack that he believes is Keyser Söze: none other than Verbal Kint. But Kujan realizes the truth too late, as Verbal has already walked out, on bail, his limp suddenly gone. He uses a gold cigarette lighter similar to one Söze was seen with at the beginning of the film to light a cigarette with a steady hand, and climbs into a car driven by the character he had referred to as Kobayashi. As they drive away, Kujan desperately looks around the crowded streets for Verbal, having realized, too late, Verbal's true identity.

Lovejoy, it doesn't seem fair that they shot the film that way, but the part you describe (Verbal "being on the dock" at the moment of the fire) was part of Verbal's lie to the investigating officer. The film was constructed by actual events in the backgrounding and action - interwoven with Verbal's story - much of which was a lie...because he was the mastermind behind the entire thing. Keyzer Soze.

Great flick, huh!