One was a parachute, sketched but not actually constructed by the real Da Vinci. But when it was eventually made and tested hundreds of years later - in the year 2000, by Adrian Nichols - it worked! And, as this Da Vinci page notes, "Despite skepticism from experts, da Vinci’s design worked as intended and Nichols even noted that it had a smoother ride than the modern parachute." The man was a transcendent genius no doubt, in our reality as well in this fine television series, where Da Vinci's parachutes enable him and his party to escape their Inca-like captors via a jump off a sheer, very high cliff, aka the vault of heaven.
The second marvelous invention which plays a pivotal role in this episode was a talking head, of Da Vinci's mother. Da Vinci neither in reality or in Da Vinci's Demons sketched or invented this device, but, as I point out in my Soft Edge: A Natural History and Future of the Information Revolution (1997), the phonograph in our reality was a mechanical invention (Edison was its inventor, in 1877), meaning it did not need electricity. Therefore, it indeed could have been invented at any time in history, and there is even some speculation that potters in the ancient world may have captured sound waves as imprints on their pottery, analogous to the grooves on vinyl records. (My novel, The Silk Code, explores this possibility.)
Significantly not discovered in this episode was the Book of Leaves, but Da Vinci is of course not discouraged but inspired to search further for it. Da Vinci and company are thus left on the shore, waiting for Amerigo Vespucci to arrive, which he does. This could have been a good final episode of this season, but there are important matters coming to the boil back in Europe.
The evil Pope treats the Turkish envoy poorly (and did I hear the Pope call one of his cardinals "Rodrigo," as in Rodrigo Borgia?), Lorenzo has increased his strength, and Lucrezia is still in Istanbul. Lots of clashes to be resolved in the next two episodes - and with Da Vinci and Giralamo now allied, their return to Europe and their impact on these clashes should be fun to see indeed.
See also Da Vinci's Demon's 2.1: Science Fiction v Fantasy ... Da Vinci's Demons 2.2: Renaissance Radio ... Da Vinci's Demons 2.3: Submarine ... Da Vinci's Demon's 2.4: Copernican Revelation ... Da Vinci's Demons 2.5: Corn ... Da Vinci's Demons 2.6: Meets Charles Dickens ... Da Vinci's Demons 2.7: Four Stories
a phonograph in ancient India in The Silk Code