The original version of autoInject unpacked arguments into the final callback. The current version does not do this:

async.autoInject({
    a: function(cb) { cb(null, 1); },
    b: function(cb) { cb(null, 2); }
}, function(err, a, b) {
    console.log('a: ' + a + ' b: ' + b);
});

Expected: a: 1, b: 2
Actual: a: [object Object], b: undefined

The documentation still refers to the original behaviour.