Two of the most striking quantum oddities are entanglement and the wave-function collapse or state vector reduction.
Firstly, quantum entanglement is the quantum phenomena involving states of composite systems. Whenever the state of the composite system can not factorize in terms of single states of the single systems, you get entangled states. These states have the odd feature that if you pick up two entangled states, for instance the Bell state, and you carry up one state to Andromeda, and other stay on Earth, you can in principle know the state on Andromeda, instantaneously, looking only at the Earth pair on Earth.
By the other hand, quantum states general live in linear superposition on certain basis when unobserved (unless you "prepare" a state before, of course). The state reduction occurs when measuring the state, and you get some of the posible states as the measurement. The reduction also happens instantaneously.
Instantaneous "things" are incompatible with Heisenberg uncertainty principle or even with special relativity (due to the finite speed of light), so, do these phenomena really occur instantaneously or are time dependent on the instrument basis used in the experiment? Why and how this instantaneous behavior is not inconsistent with Quantum Mechanics or Special Relativity?
