After Jack stops tickling Julie, she is sitting up, then sits up again.
Tom makes a joke about one candle on Jack's birthday cake before the scene with the cake and the one candle.
When Jack brings in the tray to his mum, when she's in her room, he draws back the curtains to let some light in. However, the light obviously comes not from outside, but from a source of light somewhere above (not visible).
When the mom is being lifted from the bed to the floor, it's very obvious that it's a dummy in place of the mom.