It is actually a common misconception that the saying "Religious wars are basically people killing each other over who has the better imaginary friend" was originally stated by Napoleon. The exact origin of this saying is unknown, but it first began circulating on the internet in 1999, and a massively shared Facebook post from around 2015 falsely attributed the quote to Napoleon leading to the misconception spreading.
When Holly is making tea, there is a close shot of the tea kettle spout where there is no "whistling device", yet when the water has completed boiling, a whistling sound is heard.
When Holly is making tea in Ralph's kitchen, the establishing shot of the kettle on the stove shows an open spout. A moment later, the sound of a whistling kettle is heard, not possible on a kettle with an open spout.