As far as Miranda warnings go  you probably need to first understand what they are, in order to understand what a failure to give them means. In the famous Supreme Court case Miranda v. Arizona, the courts decided that the prosecution may not use statements stemming from the interrogation of a defendant while in custody, unless the officers first it demonstrates the use of procedural safeguards effective to secure privilege against self-incrimination. Miranda v. Arizona 86 S.Ct. 1602, U.S. Ariz 1966.

In common English, this means that if the State puts you in custody somehow [i.e., you are arrested] and the police are asking you questions, they must first make sure that your 5th Amendment right not to self-incriminate is somehow protected. The courts decided that a persons 5th Amendment right to self-incrimination will be protected [when a person is in custody, and is being asked questions by the police] if the police provide a warning to them explaining what their constitutional rights are. Thus, the term Miranda warning.

Therefore, you are not going to get Miranda warnings if you are not in custody or not being interrogated.

The failure of a police officer to give you a Miranda warning while arresting you does not mean that you can get out of jail for free  it just means that you werent warned to keep your mouth shut  and if you say anything, it cant be used against you. For instance, lets say that you arrested for shoplifting, and the officer DID GIVE you a Miranda warning. If you then confessed to shoplifting, this would be a good confession and it would be admitted in court. Now lets pretend that you were arrested for shoplifting, but the officer forgot to give you Miranda warnings. If you then confessed, it would NOT BE a good confession. That is because you made your confession not fully informed of your rights, and the confession could not be used in court against you. In either case, your arrest still stands  the failure to give you a Miranda warning just limits the evidence that the prosecution can use against you in trial to prove your guilt.