Whenever I only have spells with improvise (such as Kappa Canoneer) in hand and casting them would require tapping artifacts for improvise the game automatically passes priority. For example I had 4 artifact lands (silverbluff bridge, mistvault bride, drossforge bridge and a darksteel citadel) in play as well as an unequiped cranial ram and a moonsnare protoype with 2 Kappa Canoneer in hand. At the start of my turn I drew an Island and played it and then the game passed my turn because auto-tapper had not realised I could play the kappa canoneer's.