The rapid evolution of automotive and industrial embedded systems has necessitated a paradigm shift from simple isolated controllers to complex, integrated zonal architectures. This transition is characterized by an increasing reliance on Field Programmable Gate Arrays (FPGAs), multi-core softcore processors, and sophisticated virtualization layers to manage mixed-criticality workloads. This research article provides a deep theoretical and practical exploration of fault-tolerant design methodologies, focusing on the mitigation of Soft Errors and Single Event Upsets (SEUs) at both the hardware and software levels. By synthesizing foundational theories of hardware redundancy with modern advancements in hypervisor-based isolation, this study delineates a holistic framework for dependability. We examine the evolution of fault tolerance from the early conceptualizations of failure-tolerant design to contemporary implementations in autonomous driving and Unmanned Aerial Vehicle (UAV) aided Mobile Edge Computing (MEC). The analysis covers the transition from traditional Triple Modular Redundancy (TMR) to lightweight static partitioning hypervisors and dual-core lockstep architectures. Furthermore, the paper investigates the impact of environmental factors, such as terrestrial radiation, on semiconductor reliability and the subsequent necessity for error correlation prediction. The findings suggest that a multi-layered approach-integrating hardware-level reconfigurable logic with software-level virtualization-is essential for meeting the stringent safety requirements of next-generation intelligent connected vehicles and industrial automation.