When approached by Michael Carreras to write a script for a pirate movie, Jimmy Sangster was cautioned by the producer that they couldn't afford a ship. The ship seen from long shot in the beginning was a stock shot.
The penal colony where Jonathon Standing (Kerwin Mathews) was sent to was also the Callow Hill Location. The scene of his escape and his attempted killing by two men was shot in one of the swamps at Burnham Beeches. Other scenes of the pirates wading through the swamp and walking in wooded areas was a combination of Burnham Beeches and Black Park.
When one of the pirates stomps with his foot at the bottom of the pit they're digging the sound it makes is clearly that of hollow wood.Yet he says that they have reached the bottom and there is nothing but rock(1:03:17).
When the pirates first arrive at the Huguenot fortified village they survey the area from the high hills surrounding the village(0:36:06). However, when two of the pirates and Jonathon Standing start walking down the path toward the village we notice the imposing hills surrounding the village have become mere cliffs just a few feet high from the ground (0:36:09). Also, the cliffs are located much closer to the fortified village than the imposing high hills from the previous shot.
When escaping to the swamp, Jonathan is shot in the back, yet after left for dead and continuing to escape further into the swamp, he has no wounds on his back but his left shoulder appears to be wounded on the front side.