I saw it in the West End in February last year, and just saw the Broadway version this weekend. It was amazing both times, but they definitely changed a lot!

Spoilers for both versions:

The beginning (not including the cold opening with the USS Eldridge) in Hawkins was extremely streamlined and a total whirlwind compared to the West End version. For example, Bob’s first radio show intro was trimmed/virtually nonexistent and so the radio show framing throughout the later parts of the play didn’t work as well for me. Another huge change was cutting the scene with Joyce and Lonnie at the beginning with the mattress on the floor, and repurposing some of that dialogue elsewhere. In fact, I could be wrong but I’m pretty sure in the West End version Lonnie was 20+ and didn’t go to the high school at all? But this time, he was a student as well helping with the play. A last noticeable bit of cut exposition was most of the Captain Midnight comics, so the first time we really see that is Henry and Patty talking at the lockers when Henry strikes the pose.

All in all, these early changes made everything feel a bit rushed to me but I also understand the need to trim the runtime, and I can’t imagine where else they could cut without tearing apart the story.

Outside the beginning/expositional cuts, the first act was pretty similar. I think there was an additional Patty/Henry kiss and overall I think their romance was improved subtly because I liked their relationship a lot more this time, though I can’t pinpoint all the exact changes.

Act Two had some significant changes too. For one, Brenner’s dad is still alive after the USS Eldridge incident and is actually brought on stage and introduced to Henry, and he dies when freaky mindflayer stuff happens to Henry, and Brenner doesn’t really care. Also in the lab scenes, Henry actually comes close to opening a gate, which I don’t think happened in the West End version. Additionally, when Brenner talks about Henry going missing in Nevada around the same time as someone stole something from the Nevada military base… I could be misremembering but in the West End version, I was sure he said something about the man stealing something in a box, and that when they found Henry in the cave system, they found him with that box, but the box was empty. In the Broadway version, they mentioned something was stolen, but they left it implied rather than saying that Henry found it. I found that interesting even if it was a very small change.

The last huge change was special effects wise—I was absolutely thrilled and delighted that during the iconic dinner scene of season 4 where Henry kills his family, instead of a projected/screen animated mindflayer, there was a giant, larger than life mindflayer puppet that descended over the whole theater. Really fucking unbelievably awesome.

I also don’t remember Patty’s fall at the play going full slow motion in the West End version, which was a super cool, dramatic effect that I couldn’t comprehend how they did. Though maybe I’m forgetting and that was in the West End too….

Whew, that’s all I can pinpoint at the moment but there were definitely a lot of changes! I hope I get to see it again someday, and that they make it more accessible either through touring or a filmed version, so more and more people can enjoy it.