Shadow the Hedgehog may be Sonic's most popular rival in the franchise, but another character just dethroned him as the blue blur's greatest rival.

Sonic the Hedgehog 3 started the work of diving into Shadow's story, but a key detail regarding how things went wrong with GUN was left out.

Spoilers! What happens at the end of Sonic the Hedgehog 3 and the events that take place during the mid and post-credits.

Sonic the Hedgehog 3' was "trickier" to make than the first two films. Creative partnership Pat Casey and Josh Miller have written the screenplays for all three instalments of the franchise - which is based on Sega's iconic video game series of the same name - and explained that the whole process was still "fun" but became a bit more difficult with the inclusion of new antagonist Shadow (Keanu Reeves).

Sonic the Hedgehog 3 has made over $200 million worldwide, with $137 million from the domestic market. The movie might be on track to surpass the earnings of the first two films in the series. The entire Sonic trilogy might soon reach $1 billion of revenue at the international box office.

Shadow achieves a notable transformation in the film Sonic the Hedgehog 3, as his hair fur turns white after gaining the power of the Chaos Emeralds.