The Submarine Engine is an upcoming episode.
- Bill and Ben
- Sir Topham Hatt
- Cranky (cameo)
- Big Mickey (cameo)
- Carly (cameo)
- Thomas (narration only)
- Annie and Clarabel (end segment)
- James (stock footage)
- Philip (stock footage)
- Rebecca (stock footage cameo)
- Paxton (stock footage cameo)
- Brendam Docks
- Sodor Shipping Company
- At the end of the episode, Thomas mentions the events of the twenty-second season episode, Apology Impossible. Stock footage from said Episodes was also used.
- This episode marks Hugo's first appearance in an episode and speaking role since the twentieth season episode, Hugo and the Airship. It is also his first appearance since Journey Beyond Sodor.
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