The evidence is next to him

_Elsa_

“Yeti, that sounds like a nice story,” Tiffi says. “But you’ve been here the entire time sleeping, right Pan-Pan. You ate too much chocolate. Look at all those empty candy wrappers.”

Yeti looks at her and then looks at the empty candy wrappers. No way! Penny was real and so were her friends. But the evidence is right there in front of him. He ate a lot of chocolate?? 

“Yeti you dreamt that you had travelled back in time,” says Tiffi. “Dinosaurs don’t exist anymore and you can’t time travel into the past.” 

Yeti turns on his mobile device to find out about time travel. 

‘It is uncertain if time travel to the past is physically possible. Forward time travel, outside the usual sense of the perception of time, is an extensively observed phenomenon and well-understood within the framework of special relativity and general relativity. However, making one body advance or delay more than a few milliseconds compared to another body is not feasible with current technology. As for backward time travel, it is possible to find solutions in general relativity that allow for it, such as a rotating black hole. Traveling to an arbitrary point in spacetime has very limited support in theoretical physics, and is usually connected only with quantum mechanics or wormholes.’ (Source) 

Yeti is so engrossed in reading the article that he doesn’t hear Tiffi say that she has to leave because she has to go help the players. When he looks up from his tablet he doesn’t see Tiffi. 

“Pan-Pan, did I just imagine that Tiffi was here?” questions Yeti. 

Pan-Pan confirms that Tiffi had been there and she woke him up. She couldn’t stay because she had to help some players.  

Let’s continue - The dinosaurs are dead

Start at the beginning – Yeti travels in time