Mildly Interesting

I relatively often meet 4 of these:

• no speed limit (use the normal limit for this type of road)

• car tires may defy laws of nature (slippery road, usually followed by a sign saying it applies during rain)

• speed camera ahead

• no water polluting goods (not very common, but occasionally comes up. There is also no dangerous materials with an orange trapezoid instead of an ellipse)

I also saw don't drive off the pier (around ferries), watch for skiers (in the mountains with cross-country skiing routes), and warning about planes, although in different design (around airports).

Invisible Cows sign is on the road to access Mauna Loa observatory on Hawaii

Polar bear one would be on Svalbard, and I know I've seen the crossing skier one in Norway

The penguins under car is at a blue penguin colony in Oamaru, New Zealand. Visited there in March. Might not be that exact format.

Germany has a ton of the no speed limit signs. But in reality they are just no artificial speed restriction signs, meaning drive the limit of the road type you're on.

It is real.

https://en.wikipedia.org/wiki/Magic_Roundabout_%28Swindon%29

Looks like there is one with 7 also.

https://m.youtube.com/watch?v=6OGvj7GZSIo