These are all from a site called Interesting and funny.
Although, movies are for entertainment and shouldn't be taken so seriously.

6 Movie Plot Holes You Never Noticed Thanks to Editing:

6 Plot Threads Famous Movies Forgot to Resolve:

8 Classic Movies That Got Away With Gaping Plot Holes:

The 6 Most Depressing Happy Endings in Movie History:

5 Awesome Movies Ruined By Last-Minute Changes: