A tiny Grineer emblem is visible on both sides of the weapon's receiver.
As of a recent update, the Acrid is no longer silent. It appears to be actually quite loud in game terms. This can still be countered by using the Suppress mod.
The Acrid leaves a stackable damage-over-time (DoT) effect due to its Toxin proc, which ticks 9 times over 9 seconds. Each tick deals Toxin damage.
This Damage over Time Effect is affected by Critical Strikes and Body Part Multipliers. The Damage over Time Effect will be based off of 100% of Acrid's Base Damage on a Headshot / Weakpoint. This is unique to Acrid due to the Damage over Time Effect being a fixed Percentage of the Damage the Weapon deals. (Mire may also be subject to this, as the Toxin Damage is a fixed Percentage of the Damage the Weapon deals, however requires further testing)
Enemies disintegrate when killed, similar to Saryn's Miasma. This effect is unique to the Acrid and is not shared with other Toxin weapons like the Torid or the Embolist.
As of Update 10.3, the toxin mixture in the barrel is affected by the Acrid's energy color, and the tiny explosion effect on needle impact. Note that the explosion effect is purely cosmetic.
As of Update 11.3, the Toxin effect's DoT scales with Acrid's base damage, not including elemental mods. To clarify further, onlyHornet Strike and Magnum Force directly affect the DoT. Damage per tick is 50% of this base damage (a rank 10 Hornet Strike will yield a base damage of 112, with the DoT dealing 56 Toxin damage per tick).
Oddly, despite its incredibly high base accuracy the Acrid's accuracy value is heavily degraded by Magnum Force well beyond what the mod's penalty would suggest, making the weapon highly inaccurate as a result.
To clarify on how the weapon proc works: the weapon will proc toxin on every single shot, unless another elemental status procs. So if you mod the weapon to deal only corrosive damage using an electricity mod, the weapon will proc toxin on every shot unless the corrosive procs. The proc chance listed on the weapon is actually for any other elemental damage that is created by the weapon.