lose vim colorscheme in tmux mode

I had the same problem. Only difference was I am using solarize rather then molokai.

To fix the issue, I have set up an alias in ~/.bashrc:

alias tmux="TERM=screen-256color-bce tmux"

And set up the default-terminal option in ~/.tmux.conf:

set -g default-terminal "xterm"

Lastly, do $ source ~/.bashrc to load new alias.

I tried all the solutions above and what finally worked for me is putting the following lines in .tmux.conf:

set -g default-terminal "xterm-256color"

As @romainl mentions above, I needed to force tmux to use 256 colors by adding the -2 flag:

$ tmux -2

I added alias tmux='tmux -2' to my bash_profile, so, I don't forget :)