I'm an old guy from Brisbane, Australia. As I just arrived to this forum I don't know whether somebody may have noticed this already: In Lesson 5 there is a small error in the sound of Score Reference 23 - The Legend of Tsar Saltan, Bar 2. The score is correct but the notes we hear do not match. It's on the melody in the Violins. While the notes on the score are
Eb (tied) - Eb - Eb - Ab - F - Eb - Db - Eb
what we actually hear is
Eb (tied) - C - C - Ab - F - Db - C - Eb
You may think it's just a detail but this happens to be my very favorite bit in all of RK's opus, so I couldn't help noticing.