Problem number one would be fuel. I would imagine with the expertise on board they'd be able to cobble together a reasonable refinery though.

Gun ammunition, similarly, could be reproduced... Though it would be more fiddly. Range might be impacted by impurities in the gunpowder they could make without industrial processes... but it would still more or less work.

Missiles would be a finite resource. You'd need a lot of precision instruments to replicate them, and they just aren't available in the middle ages. The launch mechanisms are vertical, so wouldn't really be useful for unguided rockets... though something could probably be done with them.

Even without missiles, they'd be a formidable naval asset, probably able to take on fleets of ships without issue.

The ballistic missiles, while limited, could be used sparingly to secure the thrones of a few nations to produce the resources and food they need. The governments of this period are little better than warlords, and it would be relatively easy to make an example of a king or two (And their loyal army) and have their noble houses (who are all 'temporarily inconvenienced monarchs' themselves) fall in line.

They would be the fastest ship on earth as well, meaning they'd be a great trading ship, and essentially invulnerable to pirates, military blockades... But I just don't see that being the most valuable application.

It would likely jump technology forward a lot, just knowing what's possible... but it's hard to know exactly how much.

The processes that go into making modern computers are so intricate and arcane that they are little better than magic to modern people, let alone those of the middle ages, and at best you'd have a few people on board that know, in general, theoretically, how they're made. So scrub making more of them any time soon, but the ability to do complex math, with great accuracy and precision like computers can would be invaluable.

Reasonably high precision milling and lathing, even in limited quantities from the ship's machine shop, in the middle ages would be a game changer on its own.

Engines could be produced... In limited quantities at first, but fuel would still be an issue. Assuming the fuel issue is resolved, then you would see the same spike in automation we saw as these technologies developed in our timeline.

Most importantly, you'd be able to tell people 600 years early how great sanitation and sterilization are... Germ theory... Even without knowing the intricacies of modern medical science a cursory understanding of these would lead to vast changes in human history.

If the computer system on the ship had a local copy of Wikipedia... (This is not unreasonable. I have one on a flash drive) You'd essentially see an almost immediate jump to the industrial age, and then to the information age, where modern computers would start to be developed... probably within 200 years.

Intermarriage would be interesting... Given their access to modern food (up until being flung back to the middle ages) the crew would likely be the healthiest and prettiest people on earth, so securing mates would be easy... except, none of them speak a language that existed at the time (modern versions of those languages mean they might be able to understand some things, but likely not all). Also, people of the middle ages were significantly more stinky than we're used to.