While we're on the subject of Viking historical trivia: A few years back I managed to get hold of a paper copy of a 1974 USGS study by Mazurski et al proposing a follow-on mission to "Viking 1975" (the mission that happened in our universe). This one would have included rovers, but otherwise would have followed the Viking profile of two orbiter/landers going into a parking orbit, making the final site selection, and then landing. That's a fundamental difference from the modern all-or-nothing direct descent profile used since Pathfinder.

I scanned the document and turned it into a PDF: Viking Rover Studies (5 megabytes). It's an interesting blast from the past--kind of a walk down an alternate memory lane of a mission that might have been; and includes several pages at the front summarizing what was known about Mars in 1974 based on Mariner results. Amazing to be reminded of how far we've come in understanding the Red Planet.

Another bit of trivia: Viking '75 had several candidate sites available, and after the orbiters arrived the finalists included a site at Cydonia very near the famous/infamous "Face". Anomalist or not, we can all wonder how history might've turned out differently if that site had been chosen for a landing.