Journey to the Center of Time (1967)

Gruff, hard-nosed new boss Stanton takes over a scientific research company upon the death of his benevolent father. Scientists Manning, Gordon and White, who are very close to a breakthrough in time travel, are told by Stanton they must have results in 24 hours or face a funding cut-off. Trying to push their equipment past its safe operating limit they travel into the far future and distant past, with Stanton along as an accidental participant, unaware that a surprise awaits them as they struggle to return to the present.