double the bass, but not double the drum?

The instrument Octavia was playing in the show was a violincello, unless the artists have never seen a cello before and decided to do limited research. The easiest way to tell the two apart are the slopes up to the finger board and the girth of the lower end on the sound board. A cello has a smooth circular curl up to the finger board and is overall smaller, but the instrument in this image has the soft almost triangular slope, so is indeed a contra bass. For reference;  
In comparison to the shows depiction;  
 
The only reason I point this out, is that I’ve been playing the cello for years. I’ve had the luxury of playing with many amazing bassists. While humans don’t usually stand when playing the cello, it can be done. My head canon is that Octavia can play more than just the cello. It only makes sense as both instruments are in the bass clef. I can play on the double bass, because of the cello. Viola and violins on the other hand…

@Background Pony #7932  
I know, but it’s a bass drum and a double bass.  
You know, two basses, double (the) bass?
 
And she plays a double bass, you don’t play a cello standing up.

@Deserter  
people argue about whether Octavia plays a double bass or a cello, but I think it’s pretty clear which one it is in this image

I’m not entirely sure the “double bass” tag isn’t a pun.