So... many, many others have written brilliant post mortems, and now that I've seen all 5 episodes, I'm not going to compete. However, I have a somewhat different complaint, that I hope others might find interesting.
Essentially, it aggravates me that the team had to be pretty incompetent for COE to play out like it did. There were just so many missed opportunities, right alongside things that worked that shouldn't have. Now obviously, these were a plot device, but it's a plot device I happen to hate. (Remember season 1, Day One, when Carys grabbed the hand and Jack yelled "Put that down. It's only important to me." From a former conman??? That's the type of thing I mean.)
1. If Ianto could track any car (as stated in Day 2) why couldn't he track the SUV. And why did he wait til he got back to the hub, then not even get on the computer to look for it?
2. Why was Jack unable to contact anyone? Are you telling me that in 100+ years, the only contact he had with UNIT was Martha, and the only government contact was Frobisher (and not even a direct line)? And what about the crown – that's where their authority comes from after all. Yup, head of a top secret agency, blocked by a sergeant and secretary.
3. When Jack knew he was about to blow up, why didn’t he give his Vortex Manipulator to Ianto? He used it to start the lift, but Ianto wasn’t out of range immediately.
4. After working together for years, Gwen and Ianto couldn't think of one place to meet without specifying the place name? WTF??
5. What about any preplanning at ALL. They're in a dangerous profession, facing aliens with who knows what capabilities and technology, and it never occurred to anyone to plan for the hub being compromised. Or for agents being outside of the hub during a lockdown.
On things that should not have worked:
6. The funeral director was tied with his hands in front of him. Um, pull off the gag? Your hands are right in front of it…
7. Jack's rescue was ludicrous without tight coordination btwn Gwen and Ianto. Consider… Gwen goes into a secure facility, and blanks a security camera. She then walks into the next room, and in full view of that camera, points a device at it, and it goes dead. Like that wasn't going to bring everyone running. As for Ianto, without Gwen and Rhys, he would have been immediately captured. The only way this makes any sense is if Gwen was a decoy to draw the guards, so Ianto could do his thing. And good thing the keys were left in the cement truck...
8. And just to nitpick, ever seen concrete being poured? It doesn't set up that fast.
9. Jack was a former conman, and indications are that his history with Torchwood wasn't exactly hearts and flowers. Wouldn't he personally, have set up false identities and bolt holes for himself? (We see Owen with a batch of fake ID's in Ghost Machine.) Also, given compound interest, the number of years he's lived and knowledge of the future, he should have accumulated enough money to pay off the national debt without half trying. It may not be a big concern for him, but I can't believe he wouldn't have squirreled away enough to run if he wanted to.
9a. If I really wanted to make Jack competent, and manage a completely different track for COE, I'd speculate that he had offsite stashes of alien artifacts that he kept from Torchwood. He was a Time Agent, and could easily have considered some things too dangerous for the timeline.
10. After the hub is very publicly destroyed, and an attempt made to kill the whole Torchwood team, there's STILL no one Jack could contact at UNIT, who might talk to him?
11 After Stolen Earth and Journey's End, he knows Sarah Jane, and knows about Mr Smith. There's another contact. Oh, and Sarah Jane showed up with a warp star in Journey's End, so Jack knows all about her having alien devices.
12. OK, I'll admit I find this hilarious, but has it dawned on everyone that the critical piece of technology (i.e. the contact lenses) required to make everything work was only available because Gwen took them home to play sex games? Now that's the Torchwood we know and love. Except why do Gwen and Rhys get kink, and Jack and Ianto get beans? No, no, NO!
13. The Torchwood thieves. Obviously played for laughs, but uh, folks... when you lift something, don't run. No better way to draw attention to yourself. Certainly Jack, as a conman should have known that.
14. Once the situation is clear, why didn't Jack try to call the Doctor? In Stolen Earth, they sent the call thru the hub, so presumably, he had the number. Even if he didn't have it from that, do you really believe he wouldn't have gotten Martha to share? And memorized it.
15. Personally, I don't see Jack as either arrogant enough or naïve enough to believe that the monsters are going to go away just because he walks in and tells them to, which rather makes the whole thing fall apart for me. Now if it was the Doctor doing the talking, he'd believe it.
16. Which brings us to: Jack’s speech facing the 456 was just lame. Basically, a powerless bluff. Why not invoke the Shadow Proclamation? Let them know he’s immortal. That he has ways to get off the planet, and contacts off world. That he'll never give up tracking them down. The result might have been the same, but at least it had a chance, and would make Jack appear dangerous rather than clueless.
17. Ianto's “Go back 150 years and see what you're facing” was a great line, but unfortunately it makes no sense. Why would the 456 have records of Jack from 150 years ago? It's not like he's on the Internet. (Interestingly, this might have worked anyway, since the 456 seem to have some psychic ability and might have picked up the intent.)
18. Shooting the tank? Really? When the 456 presumably have enough ships in orbit to transport millions of children. Yeah, that works.
18. Torchwood's computer systems have been compromised for years? I don't know about anyone else, but I really, really don’t want to believe that Tosh wouldn't have noticed. And, actually, this didn't change anything, so it was just a gratuitous slam.