Wow! Sounds like a lot of red flags that happened before the transaction, starting with the $500 deposit going over VENMO?!?!? To me that would've been a huge turnoff.
NEVER buy the car without going on a test drive. As an enthusiast, flying to the destination and driving the car back is part of the experience. They may be looking for some sucker who has more money than brains (or care) and just will throw money at an Acura dealership to fix the problems. All the panel gaps point to accident history.
However, in the dealership's defense, they are really just a business. Asking them to pay for things may sound reasonable on your side, but for them they get tons of tire kickers who are not serious and it's not worth putting up money on their side when the buyer's not serious. Until you fly there, they know you're not serious. I went through a similar situation with my recent Lexus purchase where we used an independent dealership to do a transaction on a private sale. The dealership was mad sketchy but when I got there the car looked great and what I learned was that the dealership was just very very paranoid about getting scammed themselves. We had to work out a situation where I showed him I actually had the funds in my bank account before he would accept my cashier's check. It was a long ordeal that ended well (drove the car 2k miles back) but I learned about negotiation and trusting instincts.
In your case, I would've probably paid for the gas and asked the dealer to take it for a ride. I do that for insurance purposes so that the owner knows they are covered and I can pay attention to clunks, wind noise, and electronics. When you are driving you are distracted by the road so you may miss somethings.
Again, you just have to use your instincts. When I bought my NSX I did it off-ebay because the owner was close and we were able to do the sale in person. I saved a ton of money and made a great friend in the meantime. In that case I also had the owner drive his own car to show me it was working fine. That was enough to convince me to trust him.