I noticed tat in Book 2 the "Bug Report" link had not been removed and was activated by "ESC". I only played the second half of Book 2, so I don't know if there are other bugs.
In the Book 3 Interlude when Magnus puts down the newspaper and gets up to lift Saga so that she can reach a picture on the high shelf, he floats through the wall and disappears. I had Saga exit the room and then reenter. When the action icon that appears over Saga's picture was activated, Magnus appeared again behind Saga and lifts her up.
Also in Book 3 Mr. London's energy golf ball only appears after it is caught by the Catcher Bot.