They've "referenced" older Doctors a few times this series, last week when they were on the beach he was quoting old lines and that.
I enjoyed it too tbh. Plenty of intrigue and guessing to be had, and the plot kept you interested the whole way through. We've also got the question of who "Gus" is and why he's hunting the Doctor, while the longer the ignore this Heaven place the more intriguing it gets.
I don't think he saved everyone either, tbh. He seemed to be trying too hard to make a joke about leaving them all to die in a double bluff sort of way. This Doctor also seems to be put self preservation above all, can't believe he'd waste time risking himself for so many dying people.