Lol, a few things
The mouse doesn't need the lions help and does not fear it. You see lions cannot eat mice there teath are incapable of chewing or even killing the mouse. And the mice clean the plaque off the lions teeth. Also the thorn was small which is y the lion could not remove it but the mouse could, if you could pull a lions heart out of a hole the size of needle tip you would be worshipped. Comedy was great though.