Leslie Vernon's Reliability and the Red Herring (Spoilers)
During the course of this movie, the audience is introduced to some "industry terms" that exist within the reality of this world of slashers being real people staging their kills like actors stage a theatrical production. One of the terms brought up is the Red Herring.
Now, in real life, a Red Herring is used in logic and literature as a way of drawing focus from the actual issues at hand or, in the case of books and movies, to draw the audience's focus away from the real killer. In slashers, a Red Herring is a character whom the audience is led to believe is the killer, such as in Black Christmas (1974), when we are led to believe that Peter Smythe is the real killer.
Leslie, on the other hand, refers to a Red Herring as an initial strike. In other words, he claims that either the first victim in a slasher or the act of killing that victim is the Red Herring.
It is, in a sense, related to the real-life definition in that the first victim in a slasher movie does often begin the process of misleading the audience by giving us the first glimpse of the Red Herring.
However, it also occurs to me that Leslie Vernon might be lying.
Leslie's intention is for Kelly to be the Red Herring, using the standard definition of the term. In other words, the situation is reversed: instead of the Red Herring misleading the audience to the wrong killer, in this case, it misleads the audience to the wrong heroine. Taylor is the Survivor Girl and, if we are to believe the revelations made near the end of the movie, Leslie had it planned that way the whole time. Which means we know for certain that he lied about a number of other things; he may be lying about the definition of Red Herring that he gives Taylor and her crew.
There is, perhaps, some subtle code going on between Leslie and his friend Eugene, when Eugene asks "Have you got your Red Herring all set up?" They both know that Taylor is supposed to be the real Survivor Girl, so it may be a means of bringing the issue up and deliberately misleading Taylor and company by giving a false definiton: a Red Herring for the Red Herring itself, so to speak.
Or it could be that Leslie's field of supernatural killing sprees uses the term Red Herring differently than most others.
our only salVation is in chAos and disoRder