Can you spot what's wrong with the following sentence?

PETER WAS ANGRY AT
HIMSELF BECAUSE HE
ACCIDENTALLY LEFT THE
THE KEYS TO HIS CAR
AT HIS FRIEND'S HOUSE.

I am a seven-letter word but if you remove four of my letters I will have one left. What word am I?

I have an eye but still cannot see.

Who am I?

You enter your friend's room. He is not in his room. Although you see that on the bed there are two dogs, five cats, two giraffes and three pigs. Also, a couple of chickens and ducks are flying in the room.

Calculate the number of legs standing on the floor.

I sleep during the day and fly at night, but I have no feathers to aid my flight. What am I?

How many times can you subtract the number two from the number fifty?

I am looking for a word that change both gender and number when i add the letter 'S'.

What Word am I Looking For ?

Before Mount Everest was discovered, what was the highest mountain in the world?

I am soft and cuddly that soothe your heart. But, If you pick my last name I am going to tear you all apart. Who am I?

My first is in chocolate but not in ham. My second is in cake and also in jam. My third at tea time is easily found. Altogether, this is a friend who is often around. What is it?