In every episode I've seen so far, Phineas and Ferb's creations vanish in amusing ways, when their mom gets home. And in one episode they get busted, but it turns out to be a dream. Is there any episode where they actually get busted?
Your question already refers to the episode “Phineas and Ferb Get Busted!”, in which the brothers are busted and sent to a correction facility, but the whole thing turns out to be a dream. There are at least two other episodes when Mom busts the boys.
The boys get busted twice in “Phineas and Ferb's Quantum Boogaloo”. First, Candace from the future uses a time machine to travel back to the time the boys have built a roller-coaster. She helps present Mom bust the boys. However, that ends even worse than in “Phineas and Ferb Get Busted!”, so future Candace works to get those events erased from the timeline using more time travel. The second bust is when present Phineas and Ferb and Candace travel into the future and meet their Mom. This is enough proof for Mom that they're time travelers and that Phineas and Ferb made the time machines, so Candace finally gets Mom to bust them. This, however, all happens in the future where future Phineas and Ferb are grown up, and Mom in the present never finds out about it. The bust does give Candace some satisfaction though, and a renewed resolve to try to but her brothers.
Another occasion is “She's the Mayor”, in which Mom busts Phineas and Ferb, but then an invention of Doctor Doofenschmirtz misfires and turns time back to before most of the episode has happened, so in the end Mom doesn't remember this.
Interestingly, the boys don't get busted in “Last Day of Summer”, despite that many events in the episode are undone once again by an invention of Dr. Doofenschmirtz. There are also two memorable occasions when Candace gets busted, but I don't think these answer your question.
I want to add the "Backyard Hodge Podge" from season 4.
The Mum (after a work loaded time) steps outside into the backyard and see a very big roller-coaster like invention. Candace walks aside her, but is at exactly this time hit by the "Eye-Fog-inator". As the Mum asks Candace "Do you see what I see" she must answer "No Mum, I see nothing" and the Mum goes back inside, thinking she hallucinates...