If I shot a bullet that travels backwards in time, what would it be like?

Most likely Frank.

bit harsh for that. Honest douche move right there.

too late

Or Geralt, maybe he knows

Noone ever said it wasn't

Well to be honest that doesn't really make sense. You seem to be confusing what space-time means, it is not merely New York, USA, NA, Earth and so on but also 2 of August in the year 2013. Indeed this is supported by the very idea of time travel since the possibility of time travel necessarily means time is no more than a position.

Anyway since the entire world is affected by the same forces anything on it is only perceived to move in relation to each other. In more absolute terms the entirety of the galaxy is travelling at an speed of 700 km/s or so, the solar system in it's orbit around the centre of Milky Way at about 220km/s and Earth around the Sun around 30km/s. All these speeds by definition are also included in the bullet and the interesting thing is then what happens when you start messing with time.

There are several possibilities depending on what exactly you mean by your initial question(your answer implies you are thinking of something different than what I had in mind), here are some so please tell me what is the general one(even if you disagree with my extrapolations) so I can understand which scenario you mean:

1- The bullet is under a reversed time flow much like you see in a video that you watch reverted. In other words it is not changing its position in time but rather changing the values it had(position, speed and so on) to the time it perceives as being.

Basically the bullet is travelling backwards in the sense that if a second passes for us for the bullet it will have reverted all it's values to what they were two seconds ago or a second before we start counting.

In this case you as the guy who fired the bullet would see it as stuck in a continuous loop of being fired, going back, being fire, going back and so on with the duration being double the time it takes for the effect to start(if it starts a second after it leaves then it takes a second for it go return to the gun). This would in effect cause a time loop for the bullet.

2- The bullet behaves as if in a video it was being played backwards while everything else is played normally. The bullet is altering the time it exists in but not anything else, this is the scenario I described before so I will refrain from further.

3- The bulllet was fired into the past in such a way to be basically teleportation only for it's position in time. You will see the bullet vanishing and someone in the place where it went will see it suddenly appearing. An outside observer capable of actually understanding things would clearly see it going from a position to another.

The specifics here depend on how the portal creation defines it's destination to see if the portal changes only position in time, takes into account the relative position in space(in this case in relation to what? The gun? The soil? The Bullet? The Earth? The Sun? And so) or is freely customizable to the point you could hit whatever you want whenever you want.

4- The bullet is flowing through time backwards but since all else is normal it will still be affected by all forces normally so you end up with a gun with a normal bullet then the moment it is fired there are a bunch of atoms loosely together instead there. This bizarre bullet would behave as a normal bullet in all aspects but if you were to watch wherever it has fallen you will see the atoms joining together until you perceive an extremely rusted bullet which starts to seemingly self-recover until it returns to a completely normal and usual bullet which then it promptly vanishes back to the gun(that was fired originally).

Bitches don't know about my arrow of time.

reverse physics to match reverse time. and consequently reversed line of events.. would be hilarious if you died before you where old, before having kids, before getting married, before going to college, before enjoying your infancy before being born!

but on the topic of the bullet, it would go back to the gun's chamber, then the clip, then the store,etc.. ahah it's just like you said, turning the conversation specific will make it boring and an easy answer.