Does a Vial of Acid, Oil, Alchemist Fire, or other improvised weapon adventuring gear still require an Object Interaction to 'draw' first?

Question

A specific example being Thief Rogue: If they don't have the vial in their hand at the beginning of combat, would they still need to use Object Interaction to take out the vial, and then use either a Fast Hands bonus action or an action to throw it?

And since they still only have one Object Interaction on their turn, they can't then take out another throwable and use their action or bonus action for it?

Or is taking out the acid vial or other gear baked into the action of using it, so they would be able to use their action and their Fast Hands to throw 2 throwables even if they started combat with their hands empty?

Answer 1

Retrieving a vial or flask and attacking with it requires two object interactions

Attack limits

To draw two flasks and attack with both of them you would need to be able to take four object interactions, two to draw them both, and two to throw them both. You however only have three object interactions

1. your free object interaction
2. your Fast Hands Use an Object bonus action
3. your Use an Object action

so you will not be able to draw two objects and attack with both.

Detail explanations and citations

Throwing a vial of acid, oil or alchemist fire requires an attack with an improvised weapon. In the case of these items, even though you are making an attack, this uses the Use an Object action (see details in the linked Q&A):

Acid. As an action, you can splash the contents of this vial (...)
Alchemist's Fire. (...) As an action, you can throw this flask up to 20 feet (...)
Oil. (...) As an action, you can splash the oil in this flask onto a creature (...)

The text does not state that you retrieve and throw the flask or vial, so you are spending your action exlusively to attack with it. As it is a Use an Object action, you can also use your bonus action for it, due to Fast Hands.

Retrieving an object like a flask or a vial requires its own object interaction. The Use an Object action on page 193 PHB states:

You normally interact with an object while doing something else, such as when you draw a sword as part of an attack. When an object requires your action for its use, you take the Use an Object action. This action is also useful when you want to interact with more than one object on your turn.

So you are making an attack with the object, why can't you draw it like your sword, as part of the attack? You can, but the rule for getting this free object interaction to draw the weapon with the attack is limited to one a turn. This is explained in more detail on page 190 PHB:

You can also interact with one object or feature of the environment for free, during either your move or your action. For example, you could open a door during your move as you stride toward a foe, or you could draw your weapon as part of the same action you use to attack.

If you want to interact with a second object, you need to use your action. (...) The DM might require you to use an action for any of these activities when it needs special care or when it presents an unusual obstacle.

(I think this all would be simpler to explain if the PHB just would have said that interaction with a non-magical object not covered under another actions means you take the Use an Object action, and that you can use one such action for free each turn.)

Answer 2

The rules say:

Acid. As an action, you can splash the contents of this vial (...)
Alchemist's Fire. (...) As an action, you can throw this flask up to 20 feet (...)
Oil. (...) As an action, you can splash the oil in this flask onto a creature (...)

None of these are the Use an Object action or the Attack action - they are the Acid, Alchemist’s Fire or Oil actions respectively.

As such, you can use your free object interaction to retrieve them and then their specific action to use them. You can’t use Fast Hands because there is no Use an Object action here.

Answer 3

You seem to think Fast Hands allows you to attack twice on your turn. It doesn't.

Fast Hands

Starting at 3rd level, you can use the bonus action granted by your Cunning Action to make a Dexterity (Sleight of Hand) check, use your thieves' tools to disarm a trap or open a lock, or take the Use an Object action.

Note how in that list it does not say 'attack', 'take the attack action', or any variant thereof.

Use an Object

You normally interact with an object while doing something else, such as when you draw a sword as part of an Attack. When an object requires your Action for its use, you take the Use an Object Action. This Action is also useful when you want to interact with more than one object on Your Turn.

Just to be very clear - 'use an object' refers to this. Not to attacking. Attacking is its own, special thing in D&D 5e.

Attacking is its own action. You cannot use Fast Hands to attack.

Now as for drawing multiple objects to throw them during your turn - Fast Hands could be used for that. If you have the Extra Atttack feature, allowing you to attack twice, you could draw one weapon as part of using your Action to Attack, and draw another weapon as a Bonus Action using your Fast Hands ability, thus allowing you to draw two weapons where most people could only draw one.

However, for those with multiple attacks who are throwing weapons at enemies, typically they will attempt to gain the Throwing fighting style (from Fighter and a few other places) which allows you to draw weapons as part of throwing them automatically.

If you have neither ability (or anything else that lets you draw weapons more swiftly, such as the Dual Wielder feat), you will be limited to drawing only one weapon per turn, unless you spend your Action to draw a second one via the Use an Object Action.