Lost

When discussing Locke's father's condition, Jack tells Locke, "Whatever happened, happened." This is also the name of a fifth season episode.

In the flash-sideways, Jack tells Locke that his surgery was difficult because his dural sac had ruptured. In the first episode of the series, Jack tells Kate about an incident early in his career when a patient's dural sac ruptures (as the result of his mistake) and about how he forced himself to deal with the consequences and remain calm.

When Jack gets the C-4 out of the backpack, the countdown goes from 3:55 to 3:52. It then beeps 10 times (one beep per second), leading the countdown to 3:42. However, the scene after, the countdown is at 3:45.

Jack buys an Apollo Bar from the vending machine at the hospital.

Hurley says he cannot find the First Aid Kit. The Kit can be seen in the control room next to Frank.

The Numbers:
There are 4 bricks of C-4.
The Apollo Bar is located at E3 in the vending machine. E is the 5th letter in the alphabet. 5+3=8. Also, 5x3=15.
Four people escaped from the sinking submarine.

For the first time, Andrea Gabriel ("Nadia") appears in more than one episode in the same season.

First appearance of the boat Elizabeth since "The Glass Ballerina".

This episode showed flash-sideways of the candidates (except for Hurley). The order in which they were shown is also the order of their numbers:
-Locke: 4.
-Sawyer: 15.
-Sayid: 16.
-Jack: 23.
-Jin and/or Sun: 42.

When Sawyer is talking to Jack on the sailboat, his hair changes position between the face and over-the-shoulder shots.

It took one week for someone to find Keamy's body.

The EMT mentions that Locke's wheelchair was "smashed to pieces", yet in "Everybody Loves Hugo", the wheelchair is shown intact, standing upright after the accident.

Sun and Jin could not realistically arrive at the ER at the same moment as John Locke, as the events of "The Package" take place just a day or two after the arrival of Oceanic 815 in LA, whereas Desmond's attack on Locke took place at least a week after, since Desmond tells Hurley it had been a week since their flight in "Everybody Loves Hugo". (Sawyer also tells Kate at the station it was a week since they met at LAX).

Jack first saw Christian on the fifth day after flight 815 crashed in "Walkabout" and not the third day as he recalled.

When Sawyer is steering the sailboat, from one angle there is a trailing wave, and in the following angle there is none.

Jack's chat with MIB and later with Claire takes place at night. They come back from the chat in bright daylight.

While Jack is in Ilana's office, his necktie changes position, first showing the top button and then hiding it in the next shot.

When Sun is in the hospital bed, the heart monitor shows her heart rate as 144 but the EKG shown and beeping are much slower.

The Numbers:
Claire and Desmond get off the elevator on floor 15. Claire also pressed the button at minute 15 of the episode.

When Jin and Sun meet, Sun speaks in English to Jin. Sun has not seen Jin since he learned English, though Jin had been learning some English words since the end of season 1.