In the second stage "Can't Wait To Be King", if the player fails to jump over a giraffe using the ostrich, it's possible to trap Simba on a small island with no way to continue the game.
Contributed by Mr. Kite
There was originally a meter for Scar's health during the Pride Rock level towards the end of the game, however this was removed before release.
Contributed by Dazz
Frank Klepacki, who composed the music for the SNES release of the game, received a letter from Hans Zimmer's studios complimenting him on the soundtrack for the game.
Contributed by Dazz
The monkey and bat enemies were inspired by the game Gauntlet.
Contributed by Dazz
The monkeys featured in the "Simba's Pride" level originally threw obvious feces, however Disney requested this was removed from the final release.
Contributed by Dazz
Several levels and characters that appear throughout the game come from deleted scenes from the Lion King movie. During the film's production, the transition from young Simba to adult Simba was originally much longer, and featured a number of the events that occur within the game. Because the game was being produced alongside the film, these levels were being created during the point when it was decided to have these scenes removed from the film. It was decided to keep these levels and characters kept in the game, even though they never appear in the film's theatrical release.
Contributed by Dazz
The wildebeest level was originally going to be scrapped due to the requirement for entirely new assets to be drawn as well as the thought that it would be incredibly difficult to create it with 3D-style gameplay. It was kept in after the game's programmers worked solidly day and night to create the level a week prior to the meeting in which it would be discussed, as to make sure that it was decided to keep the level in.
Contributed by Dazz
Disney's animation studio, who worked on the game alongside the developers, had qualms with the mechanic of being able to change direction while in mid-air. Their issue is that this move would be physically impossible, and from an animation standpoint, requires the graphics to jump from facing one direction to another. After a number of discussions, it was agreed to keep the ability to switch direction mid-air.
Contributed by Dazz
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The second level of the game, "Roar at monkeys, Can't wait to be king", was intentionally made to be long and complicated because at the time Blockbuster had a rental program out, and Disney had a rule across its products that a person couldn't get past a certain percentage of a game within a certain amount of time. At the eleventh hour of development, the developers decided to make the monkey puzzle in the level long and tedious and with less prompts for the obstacles so to work with that rule.

Disney believed at the time that if a person rented a game and got through it too quickly, then people possibly wouldn't buy it.
Contributed by KnowledgeBase
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There is an Easter egg in the NES version of the game which changes the skill level to 'Boy Love' when the right conditions are met.
Contributed by RadSpyro
In the NES version of the game, the wrong song (The Pridelands) is played on the Stampede level.
Contributed by RadSpyro
Microsoft DirectX was created in response to the PC port of The Lion King. The Lion King was released on Christmas 1994, and many children tried playing the game, but it would crash when loading. A Wall Street Journal article was published about someone spending his entire Christmas evening trying to get The Lion King to work for his daughter. Even Disney's helplines were flooded with phone calls. Many developers became suspicious of Windows as a viable platform, and stuck with MS-DOS. In response, Microsoft quickly developed the first version of DirectX for the upcoming Windows 95.
Contributed by rethack24