As is the case for most film criticism media, the subject of spoilers is a long-standing concern on Wittertainment.
Obviously, there are some very famous ones that require no further elaboration. But how much information is revealed on the programme about a film - either by Mark and Simon or by the listeners in emails - is a very sensitive area.
As Mark has explained on air, the rule generally is that anything in the set-up - the basic plot of the film - is ok. Anything that happens in the opening moments of the film - even if it a surprise, such as a car crash (Sir Anthony Hopkins being dead in Proof, for example) - it is usually considered safe to reveal.
There are exceptions, however. Both Mark and Simon are keen to avoid revealing details that are routinely revealed in other press reviews if it is likely to spoil key moments - such as some of the CGI work in the aforementioned Rogue One. Other times Mark will try and explain things as cryptically as possible, although this does not always work as he has Simon (as the voice of the listener) to contend with. One example: when reviewing The Ruins, Mark referred to "necrotising tendrils" to try to avoid giving too much away. This was somewhat undermined when Simon asked "does that mean the plants eat people?"
In the case of Never Let Me Go, Mark felt it would be a spoiler even to reveal what genre the film was in.
During listener correspondence in the Box Office Top 10, Simon audibly redacts spoilers that have been included in listener emails, humming over them or scribbling them out with his pen. However, on occasion he has not actually seen the film in question and it has been the case that he has accidentally revealed rather more than intended. One such instance was with A History Of Violence, which Mark (who considered it, alongside Crash (the Sandra Bullock one), the best film of 2005) had been very cagey about saying much about, other than that Viggo Mortensen would be acknowledged as the new Robert de Niro by 2010. However, Simon's reading an email from one listener saying that the film's plot was ripped off of The Long Kiss Goodnight was enough to prompt complaints from other listeners that it had given the game away.
Mark has stated that he suffered a torrent of abuse when, during an introduction of the original Ringu on Channel 4, he said "the bit when Sadako comes out of the television set is really scary"; viewers wrote in saying "not after you told us it was going to happen, it wasn't." Mark admitted this was "the most valid criticism" he had received in his career. On the other hand, he did not agree with when one person complained that he had given away too much of Audition by repeating the line "and now for the left leg."
When the film under discussion is one that is on the end of a Kermodian rant, rather more of the plot tends to be revealed. The famous review of Pirates Of The Caribbean: At World's End contained a key plot point from near the end of the film. The Last Holiday review went one better, flat out revealing whether or not Queen Latifah's character was fatally ill, for which Simon royally took him to task. (SIMON: How much time and effort went into making that film that you've now just spoiled? MARK: Very little).
Also, when a work has been around for a decent period of time in some kind of media and is broadly known, it is felt that there is little to be lost by talking about the end. There were no qualms about revealing the existence of the mother in the attic in the Jane Ayre, for example, or the bit at the end of Romeo And Juliet that gets changed in Gnomeo And Juliet. Indeed, Mark suggested that parents with concerns about how their children would deal with The Lion, The Witch And The Wardrobe could tell their children in advance that when Aslan is killed, it might not be the end of the story, what with it being a Christian allegory and everything.
When the Wittertainment audience overwhelming demands a discussion of the ending of a popular film - such as The Dark Knight Rises or Rogue One: A Star Wars Story - this is done at end of the podcast and preceded by an official BBC spoiler alert.