As some have sort of alluded to, I'm guessing the factory might try to stage certain cars in order so there is less reconfiguring between stuff in a day. Say for instance they have 10 ACRs to build and 10 normal cars. Probably makes more sense to run all the ACRs in a row just so everyone is doing the same thing several times in a row. Or maybe they might want to build cars of the same color in a row so you can grab any red panel off the rack and put it on. Since the Viper was hand built in low quantities though this might be a bit of a stretch. Not sure, but I also think they would sometimes let owners pick VIN numbers that had some kind of meaning to them. Like someone wanting a number that ended in 91 for the Le Mans car or something like that.
When and where the VIN gets assigned might also be a bit of a gray area. It is probably done fairly early as I believe the engine and transmission had some portion of the number stamped on them. You could still have a line of assembled engines and just stamp them before you install them though. Similarly you could have a line of nearly fully assembled cars and just stick the VIN plate on as you go. Guessing it might be different for every OEM as well. Where I work builds industrial trucks and there are 3+ numbers associated with every truck. There is a sales order number, a production order number, a unit effective number, and then a VIN for on-highway trucks. Doesn't help that each number is in a different system practically, so cross referencing them is a major pain. That being said, as one example of how it can be done for us, a customer might order a fleet of 20 trucks, but we might build 10 this month and 10 next month. We'll assign them sequential unit effective numbers (a number that gets stamped on the frame rail) so the customer has a nice sequence of units, but we typically don't actually build them in order. Maybe something similar happened with the Vipers where a dealer got a sequence of 10 VINs in a row, but Dodge only delivered one unit a month to the dealer or something like that.