Junior programmer pathway

Hi guys, I am currently doing the Unit 1 player control path on the Junior programmer pathway. I've reached an issue where my vehicle flies in the air when I switch to game mode, despite the code being exact in the video? Any help would be appreciated.

 using System.Collections;
 using System.Collections.Generic;
 using UnityEngine;
 
 public class PlayerController : MonoBehaviour
 {
     public float speed = 5.0f;
     public float turnSpeed;
     public float horizontalInput;
     public float forwardInput;
 
     // Start is called before the first frame update
     void Start()
     {
 
     }
 
 
     // Update is called once per frame
     void Update()
     {
          horizontalInput = Input.GetAxis("Horizontal");
         forwardInput = Input.GetAxis("Vertical");
 
     //Moves vehicle forward
         transform.Translate(Vector3.forward* Time.deltaTime* speed * forwardInput);
         transform.Rotate(Vector3.up, Time.deltaTime * turnSpeed * horizontalInput);
     }