Stargate

• Stargate SG-1 S5E3 "Ascension"
• Stargate SG-1 S4E20 "Entity"

In "Ascension", Orlin gifts Sam a sizeable emerald, claiming it to be her birth stone, implying that her birth month is May. But in "Entity", we saw that her birth date is actually in December. While I assume this was just a production mistake, if I had to come up with an in-universe justification for what we see here, I would have to assume that Orlin was just mistaken. Maybe he saw someone else's birthdate marked somewhere and he assumed it was Sam's, or he read a chart wrong and thought December was emerald. Looking at various price charts for birth stones, I see that the December stone sometimes varies, but it is always on the cheaper side of birthstones. On the other hand, May is always emerald, which is one of the most expensive birth stones. Regardless of how Orlin had made the mistake, I figure that Sam was aware that May is always a more expensive stone than December and decided not to correct him at all and just cash in on the mistake. She needs a new microwave and toaster.

Stargate SG-1 S7E9 "Avenger 2.0"

https://www.gateworld.net/sg1/s7/avenger-2-0/

In this episode, Dr. Felger comes up with a virus that is able to remotely disable stargates. After it doesn't go as planned, Sam comes in to help and we see this montage that involves writing code on a whiteboard.

I thought it was sort of silly how she wasn't just brainstorming pseudocode here, which is generally the type of thing that I see coders doing with whiteboards. No, that seems to be a full verbose script, written character-for-character. But as I looked closer, it got worse. That language seems to be C#. If we take this situation as literal as possible, that must mean the SGC had come up with some .NET-like middleware framework sort of thing for interacting with the stargate. I would imagine that there were better languages that they could have used instead.

In Stargate SG-1 S7E3 "Fragile Balance", we see a close-up of Jack's United States Air Force identification card of some sort which clearly indicates his name is "O'NEILL, JOHN J." But basically every wiki article out there about the character indicates that his name is "Jonathan".

• https://www.gateworld.net/wiki/Jack_O%27Neill
• https://stargate.fandom.com/wiki/Jonathan_J._O%27Neill
• https://en.wikipedia.org/wiki/Jack_O%27Neill

Is that correct? As far as I can tell, Jack's ID here indicates that his legal name is "John". If his legal name was actually "Jonathan", that is what would be on his military ID. Yes, most people who go by the nickname "John" are actually named "Jonathan" as their full legal name, but that is not always the case. There is no reason to assume that someone's military ID has a nickname printed on it, right? If someone's military ID indicates that their name is "John", I think it is safe to assume their full legal first name is just "John".

As far as I can tell, there is no indication in the show as to what Jack's full legal name is other than this quick closeup of his USAF ID. The only time the name "Jonathan" is ever actually spoken in Stargate SG-1 is Kinsey clearly talking to his driver in S5E10 "2001". That seems to just be a coincidence, for all we can tell. The name "John" is spoken a few times, but again, always clearly about some other person.

This concept of a legal "John" (not "Jonathan") going by "Jack" is a fairly common occurrence. Think JFK, Jack Nicholson, Jack Welch, Jack Donaghy, etc. Not as common as a legal "Jonathan" going by "John", but it happens. Jack O'Neill actually having the legal name "John" is definitely not unprecedented.

Also this: Stargate is Back (Announcement) - Dial the Gate
https://www.youtube.com/watch?v=ZfO8D0OZNMU