Various distributed sensing applications are being deployed in the context of crowd-sensing. These applications often require that sensors are mutually synchronized. However, when synchronization is required in a setting where volunteers bring their own mobile device, to contribute to a measurement campaign, several issues arise. This paper analyses and evaluates the Android mobile platform for applications which require collaborative continuous sensing. These applications rely on time synchronized devices to sample sensors at a high data rate and without discontinuities. We show that it is feasible to synchronize smartphones without limiting the system's scalability, or introducing additional power consumption. Furthermore, the challenges related to continuous sensing in Android for crowd- sensing applications are identified.