Nitpick: During the battle with the Xindi ships, Commander Tucker states "the starboard nacelle has been hit, we're dead in the water". However, in the following battle scene, Enterprise is moving and dodging enemy weapon's fire, more than could be accounted for by thrusters only.
Although they are unheard of through the 23rd and 24th centuries, according to Daniels, by the 26th century, there are Xindi serving on Federation starships.
According to Daniels, by the 26th century, the Klingons are part of the Federation.
(after hitting Enterprise with the Insectoid Shuttle)
Archer: No problem. I'll send you the bill.
Mayweather: Can I ask you something?
Archer: Go ahead.
Mayweather: You're the least expendable man on Enterprise. Why are you doing this?
Archer: An hour ago, I gave the command to kill three Xindi in cold blood. A month ago I had Phlox create a living being in order to use some of its tissue. Then I watched him put it to death.
Mayweather: Sounds like you're saying this is some sort of penance.
Archer: I'm saying I won't order anyone else to die.
Trip: What happens if you fail? Are we supposed to just keep sendin' people in 'til there's no one left?
T'Pol: That's hardly a viable option. We only have one more shuttlepod.
(Figuring out the Insectoid shuttle's controls)
Mayweather: I think I found reverse.
Trip: Great, but unless we plan to fly in ass first, we'd better figure out how to make it go forward.
(In the shuttlepod)
Travis: Your starting to think like an Insectoid.
Archer: I'll take that as a compliment.
T'Pol: Get out.
Xindi-Humanoid: We can't forget who the real enemy is!
Degra: We may not know who the real enemy is.
Archer: I've always been much better at avoiding farewells than giving them so I'm not even gonna try. But I'm going to ask all of you to think back to the day when this ship was first launched. We were explorers then. When all this is over, when Earth is safe, I want you to get back to that job. There're 400 billion stars in our galaxy. We've only explored a tiny fraction. You have a lot of work to do. Of all the captains who will sit in this chair, I can't imagine any of them being more proud than I am right now.
Reptilian Commander: When can we get underway?
Degra: Momentarily. Patience.
Reptilian Commander: Patience is for the dead.
T'Pol: He said you're the only one who can end the conflict with the Xindi. You can't do that if you're dead.
Archer: That's if you accept Daniels' version of the future.
T'Pol: He's in a position to know.
Archer: I thought you were the skeptical one when it came to time travel.
T'Pol: Our recent visit to Detroit has tempered my skepticism.
Xindi-Sloth: The last time I saw you like this was when you delivered the first weapon.
Degra: That one only killed seven million. This one will destroy an entire world.
Xindi-Sloth: Better their world than ours.
Degra: That's what I keep telling myself, but the reality is a good number of the dead will be innocents and children.
Xindi-Sloth: It's best not to think about it.
Degra: That's difficult when you have children of your own.
Xindi-Sloth: What we do is for them. For our children's future. Remember that.
Degra: I wonder how they'll remember us.
Reptilian Commander: Is this a preemptive strike?
Archer: I thought that was your specialty.
Reptilian Commander: You don't want to know my specialty.
Archer: Let me guess. Stinkin' up the room.
Archer: I'll bet you didn't know this, but at one time most of my world was ruled by reptiles.
Reptilian Commander: I wasn't aware of that.
Archer: A comet hit around 65 million years ago. Caused a mass extinction. Most of the reptiles died out. Mammals became the dominant species.
Reptilian Commander: How unfortunate.
Archer: Still, the reptiles might've come out on top if it hadn't been for a slight disadvantage.
Reptilian Commander: And what was that?
Archer: They had brains the size of a walnut. That's very small. Apparently, it's a constant in the universe.