I'm finding a few more bugs, so rather than create a thread for each, I'll list them here, and update the list as I find more.

* Rain can be seen falling through the ceiling in tunnels. If you turn your windscreen wipers off while there, Uncle will ask you to turn them back on. Rain can also be seen indoors at the Laika shop, service station and motel.
* After checking into the motel and seeing Uncle to bed, I went to the Laika shop to purchase a number of upgrades, fitted them to the car and drove it to the service station. As I parked, a message box from Uncle popped up, despite him not being in the car. Turning the radio up elicits Uncle's question of "Does it really need to be so loud?", and rolling down the window has him suggesting that I roll it back up; all while he is asleep in the motel.
* Replacement doors do not appear outside the Laika shop when ordered.
* The beds in the motel room can be walked through.
* There is a slight grammatical error in Uncle's line: "We should head to the border, oh don't forget to pick a route before we cross." It should read: "We should head to the border. Oh, don't forget to pick a route before we cross."