I bet I'm not the first one to notice the mistake on the Homepage

But I’m probably the first person to point it out. Proving that I’m either a fast-fingered, eagle-eyed ignorance fighter or an anal-retentive, nit-picking PTA.

All the way on top of the left hand corner. The first words. The little tiny ones. Instead of saying “advertisment:” it says “ruadvertisement:”
No need to thank me for pointing that out.

…there’s a homepage?

It’s not a mistake. It’s a question.

Yep.

And what makes you think it’s a mistake? It’s a perfectly cromulent word, from the Latin ruadvertisare, which in turn is formed from the Greek root ρυαδ- (“matter”) and the Old Phoenician vertisim (“wazza”).