Help my sister identify a film/tv show!

[bhamv3]

My sister sent me this message, asking me if I could help identify this movie or television show she's remembering:

So there's some people who are trying to knock out someone else, and prepared a syringe of tranquilizer or som...ething. A girl gets up from a chair (after everyone else has left having knocked the subject out somehow or something) and unsuspectingly pulls a syringe off her leg and comically limps off with one leg numb.

I'm not a big TV/movie buff, so I come to you, Halforums, for help.

 

[Fun Size]

I haven't seen it in a long time, but it might have been Planet Terror.

 

[bhamv3]

She added an additional detail:

Also, something like the perpetrator (who had prepared the syringe) was looking for the syringe, and the girl's all innocent and ignorant, and only stands up and limps away when everyone else had gone.

Oh, and she says it's not Planet Terror.

 

[Charlie Don't Surf]

It might be Mindhunters. For whatever reason, that description vaguely made me think of that movie.