Now that we've had time to re-watch episodes on DVD or re-runs...

61) Porthos got alot more air time than Spot.

62) 'Class M Planet' actually means 'Minchara Class Planet'...but we never visited Minchara.

63) Archer didn't seem to like his command chair too much. He preferred to pace the bridge or sit on the edge of it. In fact, T'Pol always sat on the edge of it, too.

64) T'Pol's eyesbrows went from human-shaped to Vulcan-shaped (upswept) after a couple seasons.

65) T'Pol is referred to as Subcommander, and the ship's science officer; Trip is the chief engineer. However, neither is referred to as the First Officer of Enterprise.

66) Despite a wealth of alien worlds from previous series, the producers mostly elected to take us to places we'd never heard about.

67) Earthships went from rocket/jet fighter design, capable of warp 2 (First Flight), to Enterprise design and warp 5 in less than 10 years.

68) Andorians listen with their ears, instead of their antenna, as previously thought.

69) There are two distinct species of Gorn.

70) Klingon ridges explained!

71) A single officer employed as helmsman and navigator seems to have been the norm, except for the era between Pike and pre-Picard.

72) Practical jackets and flashlights on landing missions were a thing of the past by the time of Kirk's voyages.

73) Deep Space 9 was originally billed as a 'darker Star Trek', but Enterprise was much darker; darker planets, darker corridors, darker caves, darker derelict spaceships...hence the flashlights.

74) The Klingon D-7 design didn't really change in a century. Yeah. Right.

75) We never did find out what ship that was in the opening credits, just prior to our first view of Enterprise. It looks like a cross between Enterprise and a Romulan Bird of Prey with multiple engines, and approaches a planet. Who is it, and what planet?

76) The series pilot (Broken Bow) gave us just tight shots of Enterprise, to keep us guessing as to what she looked like, as she sat in drydock. Unfortunately, the opening credits give us a nice, long look at her before the full-view launch, spoiling the surprise!

77) McCoy would have felt more at home around Vulcans in Enterprise's time, what with their occasional outbursts and aggressive, armed ways.

78) 'Vulcan Combat Cruiser'??? (Fallen Hero) What the--???

79) For pacificsts these Vulcans sure seemed like off-shoots of Romulans, instead of the other way around.

80) Is Surak's pacificism and Vulcan hand salute revered or not? His teachings seemed to have been set aside around tis time, if the iconic salute is considered inappropriate.

81) These people sure do eat alot. Lots of scenes in the Captain's Messhall. And human food, too! Not Antarean Chocolate Mouse, or Goraxian Lasagna, like in TNG.

82) Movie Night on Enterprise. Relatable entertainment for off-duty personnel, as opposed to 3-D chess on original Trek, or stuffy classical concerts by Data and jazz trombone by Riker on TNG.

83) Not everyone speaks English in the universe! What a surprise!

84) Continuity, continuity, continuity. Probably the most amount of references to previous series episodes of any of the Trek series, and the one that referenced the original Trek the most.

85) And yet so little of that continuity actually matched what came before... :-)

86) Letting another species die when you can save them is okay. Another species letting your people die when the other species can save your people? Well, then they're monsters!

When did the latter occur?

In Observer effect.
http://www.youtube.com/watch?v=cGs0t-kACKQ sums it up pretty good.

I think the difference is that in "Observer Effect" the Organians caused the problem.