Here is an exceedingly interesting talk by Esteemed Husband, given in New Orleans last Sunday, on undesigned coincidences in the Gospels. This is an argument that was well-known in the nineteenth century but has, for no really clear reason, simply been forgotten as time has gone on. It is a cumulative case argument that the Gospels reflect, to an important extent, independent knowledge of actual events. Please note that this argument is quite independent of one's preferred answer to the synoptic question. That is to say, even if, e.g., Mark was the first Gospel and others had access to Mark and show signs of literary dependence on Mark, the argument from undesigned coincidences provides evidence for independent knowledge of real events among the Gospel writers. There are many more of such coincidences beyond those given in the talk.
Hopefully there will eventually be links to two talks given at New Orleans Baptist Seminary on Sunday night and Monday morning, including some of the same material and a good deal of additional material. My understanding is that there may be a small fee for those downloads when they become available.