I'd like to say that most sci-fi is fiction, so there's alot of deus ex machina in it, just like Stephen King or Clive Cussler. It's just that there's more possibilities with sci-fi than real life (bummer, I know).

The ships encountering other ships, unless your David Weber (excellent series), the cosmic void seems to be filled with thousands of ships full of pirates, smugglers, merchants, and renegades. All zooming about really fast, but all within sight.

The time travel paradox crazy stuff, no. It's bad when Verne does it, but he goes into the future. Now it's like taking tea.

"More 1960s dear?"
"No thanks, I'll just have some 1870s with this paradox. (chuckles)"