ANSWER:

What kind of a question is this? A journey of such a drop can be made into a movie!

You are over thinking and Satan is messing with your head big time! No one in his right mind would allow such things to enter his mouth unless he would also entertain flies and ants entering his mouth like that!

This is gross and disgusting! Use napkins to dry your nose before praying and during prayers! 

When I rinse my nose during wudu some water stays in my nose. While I pray, this water leaks down as a drop when I perform ruku or sujood. This water touches my lips and when I say the athkar of prayer this enters my mouth and I swallow it. Similarly, some mucus also comes to my mouth this way during prayer if I have a running nose. Does this impact my prayer?