See the type of food you've had shouldn't have knocked you out of ketosis and I can't see it making you put on weight, the calorie count just isn't high enough.
I will bet you that you will be the weight you were before if not lower by the morning. All it is, is that you've had one little slip, gone into panic mode, got on the scales to check and assumed the worst has happened, it's made you put on weight. I think if you'd got on the scales before you ate it would have told you that you'd put on that 1 1/2lb already purely from the water!
I'm waffling now, lol, so I'll stop.
Let us know if that 1 1/2lb is gone tomorrow morning though won't you.