The hotel at Burgh Island, Bigbury-on-Sea, where this episode was filmed, is the one where Agatha Christie wrote the book "Evil Under the Sun".
Filmed on Burgh Island, Devon, which also inspired Christie's book "And Then There Were None".
The Burgh Island Sea Tractor featured was designed in 1969 by Robert Jackson CBE. The actual sea tractor from this period was similar but most likely a half-track with wheels only at one end.
The Italian language title for this episode is "Poirot: Corpi al sole", and it has been repeatedly aired as a stand-alone TV movie.
Originally aired on UK tv channel itv, as a one-off TV movie, not connected to any other episode, which was later retro-fitted as episode 1 of season 8, along with what became season 8 episode 2. That's why season 8 has such a huge gap between the episodes' premiere dates, at least in the UK.