This study used bibliometric analysis to investigate trends and knowledge in Industry 4.0 research. Overall Industry 4.0 research was compared with that focused on the plastics industry by using data collected from current literature in the field. The analysis was conducted using the Bibliometrix R-tool and VOSviewer software. The results indicated that: (1) “Internet of Things” was the most commonly used keyword; (2) Industry 4.0 research can be divided into clusters; (3) countries such as China and the USA dominate Industry 4.0 research; (4) Industry 4.0 research in the plastics industry is in its initial stages but is growing; and (5) there is a large difference between overall research and that in the plastics industry. A discussion of these results, including limitations and recommendations for future research, is provided.