DH is T1 and I think he's only ever disconnected once for a ride (I'll have to ask him - it may have been Mission Space?).
The first time we went, he wasn't yet on a pump. Ever since then, he's been pumping. We don't carry insulin with us during the day unless he knows that he will start to run low that day. When we do, we go straight to first aid and they store it there.
Also, we don't use the glucagon as it takes about 10-15 minutes to get the liver to release the glucose. On the advice of his endo (and numerous EMT's/paramedics), we use cake icing gel. It comes in small little tubes and can be rubbed on his gums (even if he's unconscious) and it goes straight into the bloodstream. Works very quick and no risk of vomiting.
The heat does a number on his blood sugars. They will end up all over the place. We've been fortunate for help from CM's (and other guests in line) when there was an issue (thinking of Snow White - the CM in the outside shop next to the line ran over a Coke for us).
We always pick up the little extra monitors that are the size of a vial of strips. They're small and very easy to carry with you. Just that an a lancet to take in the park.
Now, the big issues we have had. The first time I ever didn't double check how many pump changes DH packed and he ran out of them!! The company overnighted them to us - he had to take shots that time to save the reservoir for his basal until the next day. I always have him pack 1 change per day + 2 more. He has had to change some trips every day to every other day.
We did end up in the hospital one trip. The last night there, he became very ill in line for the bus back to the room. Transportation was great and ended up sending a van to return us to our hotel (which was good since we had to stop on the way back for an ambulance to come check on him - we should have had them take him to the ER then, but he thought he was feeling better after getting sick again). We had to drive around that night (after midnight) to find peanut butter and a loaf of bread - didn't realize I could have called the front desk and they would have gotten that for us. Then, he ended up sick all night and we called the front desk in the morning. They dispatched the ambulance and he was in ICU at the hospital in Celebration, FL. It was a crazy time but Disney worked with us to delay our checkout and help me get packed and out of the room (with 2 small kids).
As far as GAC goes, we never received or used one with T1. It would have been helpful, but he didn't have a need where he couldn't wait or something else. (We have used them for another family member.)
And, as others have suggested, we have never mentioned that he has T1 for a restaurant (did with the hotel for our first visit so that we would be guaranteed a fridge in the room - as they didn't back then and if you got one they cost, but not for T1's). We mentioned it once on a cruise (non-Disney) and it made for such a hassle and foods that were sometimes worse in how they treated his blood sugars that we found it better to eat like others, and cover with the insulin.