Unfortunately for Fievel, that "leaf" was actually his shirt. After being chewed on for a bit, which didn't hurt too much since she was a herbivore, he went down her throat and entered her stomach. He was pushed around in here for many hours. Eventually, he was pushed into the small intestine. He traveled through here for many hours, though not as long as in the stomach. Eventually, he reached the colon. He was pushed through the colon, getting covered in pterosaur poop. As he neared the rectum, Etta had been pooping. However, he arrived at the rectum near the end of her defecation, thus being squeezed through her anus but her cloaca closing before he could go through it.
Thus, he had to wait in her cloaca for about 36 hours, as that was how often she pooped. In the meantime, he was hit from farts from behind that came out her anus and from urine that poured from her urethra into her cloaca and out her vent. As the cloaca only opened enough for liquid to pass through, there was no way he could fit. However, something else came, something that would have gotten him enough room to pass through, if he hadn't be so caught off guard.
Fievel had already noted her lack of a penis in her cloaca, this being the first time he was inside a cloaca since he had been inside of Ichy, and had concluded that she was a female. However, he didn't quite realize what this could mean until he saw something starting to crown out of another opening that was neither her anus nor her urethra. He stared in awe as more and more of it came out. Eventually, as her cloaca started to open, he realized it was an egg. However, he was so enraptured in the process of her laying an egg, an unfertilized one like a chicken would lay, that he lost his attempt at escape.
Hours later, Etta finally defecated and he fell to the ground and was hit with urine and feces. After wiping herself, Etta flew off. Fievel washed himself off. He could tell it was getting dark and feared getting eaten in his sleep again. Also, he began to despair of ever finding the time machine. However, in the dark he brushed up against something hard and metal. With shock, he realized it was the time machine and quickly ran into it. Thankfully, he knew how to read and was able to set it to return him back to the 1800's in the AD era.
He arrived a second after the scientist had sent him away. "Damn, this thing doesn't work!" the scientist cursed in disgust, thinking Fievel had been sent back around. Fievel left the room and soon found his father.
"I'm back! I'm back! I'm sorry I was gone so long!" he cried.
"You were only gone five minutes." Papa Mousekewitz said. "Where did you go?"
"Um," Fievel sighed, "never mind, you'd never believe me anyway."