Mars landing hoax

The Mars landing hoax is a type of denialism conspiracy theory cut from a similar cloth as the Moon landing hoaxes, where the supporters deny any probe or rover has ever been sent to Mars, alternatively claiming that footage from the Mars landings is completely (or at least substantially) faked. Some supporters, such as those within the Flat Earth Society or Above Top Secret readership also deny the rest of the space program.

Motives to deny
Some of the supporters behind this conspiracy believe that space travel in general (or at least space travel beyond Low Earth Orbit) was impossible or at least way too difficult to succesfully pull off, and this would include the Unmanned Mars Landings. Others may believe some or all Martian probes did indeed arrived to their destined locations but the footage was faked to prevent people knowing about vast alien cities. These last few people may have been inspired by the Face on Mars, Edgar Rice Burroughs's Barsoom stories and Orson Welles' The War of the Worlds.

Atmosphere
The Atlantean Conspiracy attempts to debunk claims of Mars landings by saying that the atmosphere is so thin that NASA would not have bothered using parachutes at all if this was a real mission.

Devon Island
Some 'Mars Landing Hoax' supporters have discovered that NASA and other space agencies use places, such as Devon Island and other similar deserts, to test their rovers and potential future Mars astronauts. This is because Devon Island is very geographically and visually similar to the Martian surface, making it the best Earth analogue that there is and thus a great way to test Martian technology. It further helps that it is the largest uninhabited island in the world.

The hoax supporters however believe that these places aren't used for training purposes, but instead are the filming locations for the Mars rover footage. However, if this were true, we would expect to see any recognizable Devon Island geography or mountains in any of the Martian photographs, or witness any phenomenon in the footage that would prove it actually being filmed back on Earth in the open. This is however not the case.

Some of the hoax supporters may counteract by claiming that the Devon Island footage is later modified using CGI to better fit the Martian landscape, but wouldn't it have made better sense to cut the middle-man and make it all with CGI?