Alarm clock

Death

Both of them will stay as-is because they are statues!

Snake

Once the guard goes into the bunker, the man will start moving from Mexican to American border on the bridge. Just at around 2.5 minutes, the person will turn and start moving towards Mexican border.
In another half a minute, the guard will be out and he will see the man moving towards him. Hence, the guard will assume that the person has come from the other side (total time 3 minutes).

The guard will send back the person to the American border. This way, he can cross the border.

The letter ‘D’

Envelope

Mouse

1694

Chef killed Mr. John.

Mr. John was killed in the afternoon while the chef said that he was cooking breakfast!