Bonus ending:
Find all nine life upgrades before beating the game.
Shining sword:
You get only one shot at this: In the Mystic Caves when you pass the first locked gate you'll come to a pit with a switch. There's a piece of wall you can break down there with the scorpion sword. Break the wall, break the weapon rack and get the sword.
Teddy bear:
You must get this before you find The Mask. Near the top of the present-day Mechanical Pit there's a room with a fireplace. A passageway leads out that ends in a watery pit. Head down there, use the scorpion sword to break the wall in the water pit, and then break the weapons rack to get the bear.
White Glove:
You get only one shot at this: After the prince's little "depression" you have to run from the Dahaka 3 times. The 2nd and 3rd time, each pathway split in 2 eventually. There are 2 paths, a right and left one. Next to the left one there is a weapons rack in front of a big gate. Break it and you will see a big, white glove. Be careful, if you don't do this quickly enough you will probably get sucked in by the Dahaka.
Garden Flamingo:
You must get this before you find The Mask. Go to the Hanging Garden in the present. It is behind a wall in the first alcove you come to, heading towards the huge ladder in the past.
Hockey Stick:
Go to the Central Hall in the past and move the switch towards the Hourglass Room. Take that new path and get to the breakable wall at the room's end.