The bartender spitting into Homer's drink before he forgets everything is a reference to the movie "Memento".
Homer grows fast-forwarded is the music video Everyday by Carly Comando.
At the end of "Picture A Day for 39 Years" scene there's a YouTube replay parody with the exact 50 seconds listed as how long the scene lasts which is true. The bottom of the video list is a video of "Kitten Smokes on Toilet" which has an incredibly more views than the scene.
While falling, Homer's life flashes before his eyes. The scene is a parody on the popular YouTube video by Noah Kalina which features a fast montage of thousands of pictures of him spanning a period of six years all played sequentially.
When Chief Wiggum asks Homer who the Jack the Ripper is, Homer says it's the queen's private surgeon. Referencing theories about the murderer that he was connected to the royal family which was why he wasn't caught.
Julio's revealed to originally from Costa Rica, when he's with a group of Mexicans beating up Krusty the Clown for his offensive jokes towards Hispanic-Americans.
This is the last episode to air in 2007.
This is the second Homer tries to jump off the only bridge outta town, the first being Homer's Odyssey, but in that episode he didn't succeed in jumping.
In the "Picture a day for 39 years" it reveals that Homer failed the second grade. Homer would be smart at that time from the Simpsons gene shown in "Lisa the Simpson". This explains the Simpsons gene doesn't affect the whole series.
During "Picture A Day for 39 Years" part, Homer makes a Pyramid, The Taj Mahal, and The Brooklyn Bridgeout of "Duff" beer cans.
In the "Picture A Day for 39 Years", there are versions of Homer from previous episodes.
Other pictures includes him dressed up various ways not from episodes, for example, Homer was dressed as Santa, but probably it came from "'Tis the Fifteenth Season", because Homer was dressed as Santa there.
One of the snow statues in the sledding scene was the Kool Aid guy from Family Guy.
In Homer's memories, he was shown diving naked near a cliff, but he couldn't have remembered that because it was in a dream that Marge had in church. There's also another memory from Martin's dream from Treehouse of Horror VI. It is possible that Homer imagined them separately.
Through the first two acts, as well as during Homer's cascade, it is winter in Springfield and the snow falls in many scenes, if not it is on the ground. In the party boat scene, all of a sudden there is no precipitation and everyone is dressed lightly as if it were a warm, pleasant night (not to mention it would be weird to be partying on a ship's deck in cold weather).
After Homer jumped on the boat, you can see the boat is far away from the bridge.