We know that to be kosher, a Sefer Torah must not have any mistake in it - even a single letter missing or added will invalidate it. There is an opinion that this is in regards to the mitzvah of writing a kosher Sefer Torah. They hold that if one finds a mistake whilst reading it, one is allowed to continue. Whilst this is a minority view, we can rely on this leniency under some circumstances that we describe in this podcast.