But one thing above all has got fans talking - the environmental themes of the episode and the speech made by the Doctor as the episode drew to a close.
After the imminent threat of the Dregs had been dealt with, Jodie Whittaker's Doctor turned to her companions (and the viewers at home) and delivered an impassioned message.
"I know what you’re thinking – but it’s one possible future. It’s one timeline," she said.
"You want me to tell you that Earth’s gonna be OK, 'cause I can’t.
"In your time, humanity’s busy arguing over the washing up while the house burns down. Unless people face facts and change, catastrophe is coming.
"But it’s not decided. You know that. The future is not fixed, it depends on billions of decisions and actions, and people stepping up.
"Humans. I think you forget how powerful you are. Lives change worlds. People can save planets, or wreck them. That’s the choice. Be the best of humanity."
When it came to the speech, and the episode as a whole, viewer reaction was decidedly mixed. While many praised the episode for seriously addressing the issue of climate change, others felt that it was a little heavy-handed and on the nose.
Twitter page The Women of Who came out in support of the message, with a tweet reading, "Doctor Who, not holding back on its strong views
Another Twitter user added, "Just watched @DoctorWho's latest episode and what a good episode on #climatechange, reminding us that we should act now before our planet becomes inhabitable for all species. The future isn't set, but we have to make our decisions now."
And even Extinction Rebellion got in on the act, with the campaigning group's Havering branch writing, "Couldn't agree more with The Doctor #DoctorWho #ClimateChange #ClimateEmergency #ClimateCrisis #AustralianFires #StopAdani."
However, the praise was not unanimous, with many viewers agreeing with the content of the speech but taking issue with the way it was delivered.
One Twitter user claimed, "I am trying so hard to be positive about #DoctorWho but it gets harder...#orphan55 was a really good sci fi idea, but the writing...you can present those sociological themes without delivering patronising speeches to the audience..."
Another user wrote, "It's not the fact climate change was mentioned in the episodes. Doctor Who has always brought up political issues (etc), no-one is denying that. The issue is the complete lack of subtlety now, so much so that it feels very preachy - and depressing; no proper resolution in the ep."
And a third user went on to tweet, "Well #DoctorWho was pretty good. However, that last monologue felt so shoved down my throat. The climate change centric episode would have worked better as a Sea Devil story later down the line in the series."
Despite the divided reactions, one thing's for sure - the episode certainly got people talking...