The Premise/The Ending
What I like best about this movie is the overall realism. The spiders didn't escape from a reasearch lab. There were no evil government agents. The Army wasn't dispatched to deal with the invasion. No one came up with an ingenious way to stop the spiders. The way it is dealt with in KINGDOM OF THE SPIDERS is exactly how I would expect a tarantula invasion in Arizona to be. Not even the radio DJ knew that anything was wrong!! The townfolk were helpless!!
I'm going to assume, however, that the townsfolk could have simply stomped on all the spiders before they had a chance to amass themselves into an unstoppable army. While holed up in the cottage, the survivors decide against leaving in the RV because there are too many outside and they'll never make it. But with the chemical fire extinguishers, they COULD have made it to the RV and driven off to safety.
Of course, seeing them escape would have taken away from the effectively creepy ending. Yes, it's a painting...but it's what the painting suggests that sends shivers down my spine. I suppose while watching this for the first time many many years ago, I expected maybe the army to show up with flamethrowers...or when Shatner looks out the window to see all the spiders dead. But no. I wish filmmakers had the balls to end movies like this nowadays.
Just some thoughts.