Regarding labels, all labels are subject to approval by the TTB. (Not ATF. TTB, or more fully, the Alcohol and Tobacco Tax and Trade Bureau, was split off from what is now ATFE, in the Homeland Security re-organization of 2003.)
Simply to submit a label for approval, you must have a Federal Basic Permit, along with various other federal approvals. Even if you're simply a "rectifier" (someone who blends and bottles, with no distilling) you need state and local permits as well. Labels generally have to be registered on the state level as well. This varies by state, but usually involves submitting your COLA (TTB certificate of label approval) to the relevant state agency and paying a fee.
There are also standards of fill and alcohol content, although that's kind of irrelevant, as the operation was illegal from the get-go.
As others note, the labels themselves probably weren't compliant with applicable law, (CFR 27) although again, that's also beside the point. For those curious, download the TTB's "Beverage Alcohol Manual, Volume 2, Distilled Spirits." It explains all the requirements. There's a learning curve. Even if you follow all the rules, your label may get sent back for revisions. I have yet to get one through on the first try.
Even if you give spirits away, some states have laws regarding advance notification of the state alcohol authority. You might also need to have bartenders with "responsible vendor" certification pouring the drinks. Of course, you have to be licensed to submit this notification, although some jurisdictions allow for unlicensed parties to obtain "special event" permits.
In summary, OP most likely broke a bunch of laws. On the bright side, they will probably get away with it, as the TTB is overworked and probably won't bother with something this penny-ante. A more likely danger is the state alcohol agency.
My advice? Don't pull this kind of stunt again. If you really must, work with a licensed DSP (distilled spirits plant).
Source: I'm a distiller.