How to push an array of objects into an array in mongoose with one call?

I need to push multiple values into an array in mongoose using one call. I tried doing it using a smaller array but the array is getting inserted as a sub-array.

var kittySchema = new mongoose.Schema({
        name: String,
        values: [Number]
});

var Kitten = db.model('Kitten', kittySchema);
Kitten.update({name: 'fluffy'},{$push: {values:[2,3]}},{upsert:true},function(err){
        if(err){
                console.log(err);
        }else{
                console.log("Successfully added");
        }
});

The result of the calling the above code thrice gives the below result:

{ "_id" : ObjectId("502b0e807809d79e84403606"), "name" : "fluffy", "values" : [ [ 2, 3 ], [ 2, 3 ], [ 2, 3 ] ] }

Whereas what I want is something like this:

{ "_id" : ObjectId("502b0e807809d79e84403606"), "name" : "fluffy", "values" : [ 2, 3 ,2 ,3, 2, 3] }

Another thing I noticed was that the type in the array (values) is specified as Number, then wouldnt the 'strict' option ensure that anything other than Numbers are not inserted ? In this case another array is being allowed to be inserted.

(Dec-2014 update) Since MongoDB2.4 you should use:

Kitten.update({name: 'fluffy'}, {$push: {values: {$each: [2,3]}}}, {upsert:true}, function(err){
        if(err){
                console.log(err);
        }else{
                console.log("Successfully added");
        }
});

Deprecated see other solution below using $push $each

Your example is close, but you want $pushAll rather than $push to have each value added separately (rather than pushing another array onto the values array):

var Kitten = db.model('Kitten', kittySchema);
Kitten.update({name: 'fluffy'},{$pushAll: {values:[2,3]}},{upsert:true},function(err){
        if(err){
                console.log(err);
        }else{
                console.log("Successfully added");
        }
});

Or use the $each modifier with $addToSet:

https://docs.mongodb.com/manual/reference/operator/update/addToSet/#each-modifier

// Existing tags array
{ _id: 2, item: "cable", tags: [ "electronics", "supplies" ] }

// Add "camera" and "accessories" to it
db.inventory.update(
   { _id: 2 },
   { $addToSet: { tags: { $each: [ "camera", "accessories" ] } } }
 )